<rss xmlns:atom="http://www.w3.org/2005/Atom" version="2.0"><channel><title>C++ - 标签 - 菠菜眾長</title><link>https://lruihao.cn/tags/c++/</link><description>C++ - 标签 - 菠菜眾長</description><generator>Hugo -- gohugo.io</generator><language>zh-CN</language><managingEditor>1024@lruihao.cn (Lruihao)</managingEditor><webMaster>1024@lruihao.cn (Lruihao)</webMaster><lastBuildDate>Fri, 10 Aug 2018 22:11:00 +0000</lastBuildDate><atom:link href="https://lruihao.cn/tags/c++/" rel="self" type="application/rss+xml"/><item><title>石子阵列（组合数学）</title><link>https://lruihao.cn/posts/nowcoder157a/</link><pubDate>Fri, 10 Aug 2018 22:11:00 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/nowcoder157a/</guid><description><![CDATA[<p>链接：https://www.nowcoder.com/acm/contest/157/A<br>
来源：牛客网</p>
<h3 id="题目描述">题目描述</h3>
<p>xb 有 m 种石子，每种无限个，Ta 想从这些石子中取出 n 个，并按顺序排列起来，为了好看，相邻的石子不能相同。xb 想知道有多少种排列的方法。</p>
<h3 id="输入描述">输入描述：</h3>
<p>第一行有两个正整数 n，m。</p>
<h3 id="输出描述">输出描述：</h3>
<p>第一行一个整数，表示在 m 种石子中取出 n 个的排列方案数模 1000000007 后的值。</p>
<h3 id="示例-1">示例 1</h3>
<p>输入</p>
<pre><code>1 1
</code></pre>
<p>输出</p>
<pre><code>1
</code></pre>
<h3 id="示例-2">示例 2</h3>
<p>输入</p>
<pre><code>2 3
</code></pre>
<p>输出</p>
<pre><code>6
</code></pre>
<h3 id="示例-3">示例 3</h3>
<p>输入</p>
<pre><code>3 3
</code></pre>
<p>输出</p>
<pre><code>12
</code></pre>
<h3 id="备注">备注：</h3>
<p>对于 100%的测试数据：<br>
1 ≤ n, m ≤ 1000<br>
数据量较大，注意使用更快的输入输出方式。</p>
<p>水题。</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">long</span> <span class="kt">long</span> <span class="n">n</span><span class="p">,</span><span class="n">m</span><span class="p">,</span><span class="n">ans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%lld%lld&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">n</span><span class="p">,</span><span class="o">&amp;</span><span class="n">m</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="n">ans</span><span class="o">=</span><span class="n">m</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="n">ans</span><span class="o">=</span><span class="p">(</span><span class="n">ans</span><span class="o">*</span><span class="p">(</span><span class="n">m</span><span class="o">-</span><span class="mi">1</span><span class="p">))</span><span class="o">%</span><span class="mi">1000000007</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">printf</span><span class="p">(</span><span class="s">&#34;%lld</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">,</span><span class="n">ans</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>Dreamoon and Stairs</title><link>https://lruihao.cn/posts/codeforces476a/</link><pubDate>Fri, 10 Aug 2018 20:13:08 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/codeforces476a/</guid><description><![CDATA[<p><strong><a href="https://codeforces.com/contest/476/problem/a"target="_blank" rel="external nofollow noopener noreferrer">题目链接<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></strong></p>
<p>Dreamoon wants to climb up a stair of n steps. He can climb 1 or 2 steps at each move. Dreamoon wants the number of moves to be a multiple of an integer m.</p>
<p>What is the minimal number of moves making him climb to the top of the stairs that satisfies his condition?</p>
<h3 id="input">Input</h3>
<p>The single line contains two space separated integers n, m (0 &lt; n ≤ 10000, 1 &lt; m ≤ 10).</p>
<h3 id="output">Output</h3>
<p>Print a single integer — the minimal number of moves being a multiple of m. If there is no way he can climb satisfying condition print  - 1 instead.</p>
<h3 id="examples">Examples</h3>
<h4 id="input-1">input</h4>
<pre><code>10 2
</code></pre>
<h4 id="output-1">output</h4>
<pre><code>6
</code></pre>
<h4 id="input-2">input</h4>
<pre><code>3 5
</code></pre>
<h4 id="output-2">output</h4>
<pre><code>-1
</code></pre>
<h3 id="note">Note</h3>
<p>For the first sample, Dreamoon could climb in 6 moves with following sequence of steps: {2, 2, 2, 2, 1, 1}.<br>
For the second sample, there are only three valid sequence of steps {2, 1}, {1, 2}, {1, 1, 1} with 2, 2, and 3 steps respectively. All these numbers are not multiples of 5.</p>
<p>有一个 n 级台阶，每次可以走一级或两级，问最少的步数是多少，且步数必须是 m 的倍数。<br>
找一下数学公式就好了。<br>
具体看代码。</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">x</span><span class="p">,</span><span class="n">n</span><span class="p">,</span><span class="n">m</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">n</span><span class="o">&gt;&gt;</span><span class="n">m</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">n</span><span class="o">&lt;</span><span class="n">m</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">cout</span><span class="o">&lt;&lt;-</span><span class="mi">1</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">n</span><span class="o">==</span><span class="n">m</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">n</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">n</span><span class="o">%</span><span class="mi">2</span><span class="o">==</span><span class="mi">0</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">x</span><span class="o">=</span><span class="n">n</span><span class="o">/</span><span class="mi">2</span><span class="o">%</span><span class="n">m</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">x</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span> <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">n</span><span class="o">/</span><span class="mi">2</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span> <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">n</span><span class="o">/</span><span class="mi">2</span><span class="o">+</span><span class="n">m</span><span class="o">-</span><span class="n">x</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span><span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">n</span><span class="o">%</span><span class="mi">2</span><span class="o">!=</span><span class="mi">0</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">x</span><span class="o">=</span><span class="p">(</span><span class="n">n</span><span class="o">/</span><span class="mi">2</span><span class="o">+</span><span class="mi">1</span><span class="p">)</span><span class="o">%</span><span class="n">m</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">x</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span> <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">n</span><span class="o">/</span><span class="mi">2</span><span class="o">+</span><span class="mi">1</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span> <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="p">(</span><span class="n">n</span><span class="o">/</span><span class="mi">2</span><span class="o">+</span><span class="mi">1</span><span class="p">)</span><span class="o">+</span><span class="n">m</span><span class="o">-</span><span class="n">x</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>Dreamoon and WiFi（组合数学）</title><link>https://lruihao.cn/posts/codeforces476b/</link><pubDate>Fri, 10 Aug 2018 17:44:47 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/codeforces476b/</guid><description><![CDATA[<p><strong><a href="https://codeforces.com/contest/476/problem/B"target="_blank" rel="external nofollow noopener noreferrer">题目链接<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></strong></p>
<h3 id="题目大意">题目大意</h3>
<p>就是给定两个字符串，第一个字符串由&quot;+&quot;,&quot;-&ldquo;组成，第二个字符串由&rdquo;+&quot;,&quot;-&quot;,&quot;?&ldquo;组成，“+”代表加 1，&rdquo;-&ldquo;代表减一，“?&ldquo;代表可取正也可取负，问第二个字符串的位置和第一个字符串相等的概率是多少。</p>
<p>我一开始的想法是把（+1，-1）^n 看成和二项式定理一样的展开始式，只不过把乘法改为加法，然后得到公式<br>
<code>c(n,0)(n+(-1)0)+c(n,1)(n-1+(-1)1)+c(n,i)(n-i+(-1)i)+...+c(n,n)(n-n+(-1)n)</code><br>
化简一下可知通项为<code>c(n,i)(n-2*i)</code><br>
然后我对第一个串求出位置 sum, 第二个串先求出已知位置 sum1，然后记录下？的个数，然后遍历找出展开式中某一项 n-2i+sum1==sum，这样 x 的系数就是可能出现位置相等的所有情况，用 (n-2i)/系数和就是概率了啊，可是为什么不对呢，本地调试，数据没问题，可是交到 cf 上第二组都过不了，烦亏我还觉得想到一个独辟的方法呢，过不了。</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-fallback" data-lang="fallback"><span class="line"><span class="cl">//cf 错误报告，思前恐后不晓得 why,wtf??? 先码着吧
</span></span><span class="line"><span class="cl">Test: #2, time: 0 ms., memory: 0 KB, exit code: 0, checker exit code: 1, verdict: WRONG_ANSWER
</span></span><span class="line"><span class="cl">Input
</span></span><span class="line"><span class="cl">+-+-
</span></span><span class="line"><span class="cl">+-??
</span></span><span class="line"><span class="cl">Output
</span></span><span class="line"><span class="cl">-0.000000000000
</span></span><span class="line"><span class="cl">Answer
</span></span><span class="line"><span class="cl">0.500000000000
</span></span><span class="line"><span class="cl">Checker Log
</span></span><span class="line"><span class="cl">wrong answer 1st numbers differ - expected: &#39;0.5000000&#39;, found: &#39;-0.0000000&#39;, error = &#39;0.5000000&#39;</span></span></code></pre></td></tr></table>
</div>
</div><h3 id="错误代码">错误代码</h3>
<div class="highlight" id="id-2"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span><span class="lnt">33
</span><span class="lnt">34
</span><span class="lnt">35
</span><span class="lnt">36
</span><span class="lnt">37
</span><span class="lnt">38
</span><span class="lnt">39
</span><span class="lnt">40
</span><span class="lnt">41
</span><span class="lnt">42
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="n">using</span> <span class="n">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">i</span><span class="p">,</span><span class="n">j</span><span class="p">,</span><span class="n">cnt</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">long</span> <span class="kt">long</span> <span class="n">c</span><span class="p">[</span><span class="mi">11</span><span class="p">][</span><span class="mi">11</span><span class="p">],</span><span class="n">sum</span><span class="o">=</span><span class="mi">0</span><span class="p">,</span><span class="n">sum1</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span> <span class="n">i</span> <span class="o">&lt;</span> <span class="mi">11</span><span class="p">;</span> <span class="n">i</span><span class="o">++</span><span class="p">){</span><span class="c1">//杨辉三角
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>        <span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="p">][</span><span class="mi">0</span><span class="p">]</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="p">][</span><span class="n">i</span><span class="p">]</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">j</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span> <span class="n">j</span> <span class="o">&lt;</span> <span class="n">i</span><span class="p">;</span> <span class="n">j</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="p">][</span><span class="n">j</span><span class="p">]</span> <span class="o">=</span> <span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="o">-</span><span class="mi">1</span><span class="p">][</span><span class="n">j</span><span class="p">]</span> <span class="o">+</span> <span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="o">-</span><span class="mi">1</span><span class="p">][</span><span class="n">j</span><span class="o">-</span><span class="mi">1</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="n">string</span> <span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">a</span><span class="o">&gt;&gt;</span><span class="n">b</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="c1">//cout&lt;&lt;a&lt;&lt;endl&lt;&lt;b&lt;&lt;endl;
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>    <span class="kt">int</span> <span class="n">len</span><span class="o">=</span><span class="n">a</span><span class="p">.</span><span class="nf">length</span><span class="p">();</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">len</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">a</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">==</span><span class="sc">&#39;+&#39;</span><span class="p">)</span> <span class="n">sum</span><span class="o">+=</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span> <span class="n">sum</span><span class="o">-=</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">b</span><span class="p">.</span><span class="nf">length</span><span class="p">();</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">b</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">==</span><span class="sc">&#39;+&#39;</span><span class="p">)</span> <span class="n">sum1</span><span class="o">+=</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">b</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">==</span><span class="sc">&#39;-&#39;</span><span class="p">)</span><span class="n">sum1</span><span class="o">-=</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">b</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">==</span><span class="sc">&#39;?&#39;</span><span class="p">)</span> <span class="n">cnt</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">sum</span><span class="o">==</span><span class="n">sum1</span><span class="o">&amp;&amp;</span><span class="n">cnt</span><span class="o">==</span><span class="mi">0</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="nf">printf</span><span class="p">(</span><span class="s">&#34;1.000000000000</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">        <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">flag</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">x</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">j</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">j</span><span class="o">&lt;=</span><span class="n">cnt</span><span class="p">;</span><span class="n">j</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="n">x</span><span class="o">+=</span><span class="n">c</span><span class="p">[</span><span class="n">cnt</span><span class="p">][</span><span class="n">j</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="c1">//cout&lt;&lt;x&lt;&lt;endl;
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>    <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">cnt</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">cnt</span><span class="o">-</span><span class="mi">2</span><span class="o">*</span><span class="n">i</span><span class="o">+</span><span class="n">sum1</span><span class="o">==</span><span class="n">sum</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="n">flag</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="kt">long</span> <span class="kt">double</span> <span class="n">y</span><span class="o">=</span><span class="n">c</span><span class="p">[</span><span class="n">cnt</span><span class="p">][</span><span class="n">i</span><span class="p">]</span><span class="o">*</span><span class="mf">1.0</span><span class="o">/</span><span class="n">x</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="nf">printf</span><span class="p">(</span><span class="s">&#34;%.12llf</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">,</span><span class="n">y</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="o">!</span><span class="n">flag</span><span class="p">)</span><span class="nf">printf</span><span class="p">(</span><span class="s">&#34;0.000000000000</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div><p>想不通，没办法只好换思路。</p>
<p>我先分别记下 a,b 串的&rsquo;+&rsquo;,&rsquo;-&rsquo;,&rsquo;?&lsquo;个数，然后后我们很容易知道，如要 a,b 位置相等，则加号和减号的数目，两串要相等，且 a 中的加号要比 b 中已知的加号要多，减号也要比 b 中已知的要多，否则打死都不会相等的，仔细比划一下就知道了。然后有 z 个‘?’，相当于有 z 个坑，让我们去填使得 a,b 相等。只能填+或-，设加号差等于 x-p, 所以概率就等于 c(z,x-p)/2^z。</p>
<h3 id="ac-代码">AC 代码</h3>
<div class="highlight" id="id-3"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span><span class="lnt">33
</span><span class="lnt">34
</span><span class="lnt">35
</span><span class="lnt">36
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="n">using</span> <span class="n">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="n">string</span> <span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span>  <span class="n">x</span><span class="p">,</span><span class="n">y</span><span class="p">,</span><span class="n">z</span><span class="p">,</span><span class="n">p</span><span class="p">,</span><span class="n">q</span><span class="p">,</span><span class="n">c</span><span class="p">[</span><span class="mi">11</span><span class="p">][</span><span class="mi">11</span><span class="p">],</span><span class="n">i</span><span class="p">,</span><span class="n">j</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span> <span class="n">i</span> <span class="o">&lt;</span> <span class="mi">11</span><span class="p">;</span> <span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="p">][</span><span class="mi">0</span><span class="p">]</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="p">][</span><span class="n">i</span><span class="p">]</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">j</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span> <span class="n">j</span> <span class="o">&lt;</span> <span class="n">i</span><span class="p">;</span> <span class="n">j</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="p">][</span><span class="n">j</span><span class="p">]</span> <span class="o">=</span> <span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="o">-</span><span class="mi">1</span><span class="p">][</span><span class="n">j</span><span class="p">]</span> <span class="o">+</span> <span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="o">-</span><span class="mi">1</span><span class="p">][</span><span class="n">j</span><span class="o">-</span><span class="mi">1</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">a</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">b</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">x</span><span class="o">=</span><span class="n">y</span><span class="o">=</span><span class="n">z</span><span class="o">=</span><span class="n">p</span><span class="o">=</span><span class="n">q</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">a</span><span class="p">.</span><span class="nf">length</span><span class="p">();</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">a</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">==</span><span class="sc">&#39;+&#39;</span><span class="p">)</span> <span class="n">x</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span> <span class="n">y</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">b</span><span class="p">.</span><span class="nf">length</span><span class="p">();</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">b</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">==</span><span class="sc">&#39;+&#39;</span><span class="p">)</span> <span class="n">p</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">b</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">==</span><span class="sc">&#39;-&#39;</span><span class="p">)</span> <span class="n">q</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span> <span class="n">z</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">x</span><span class="o">==</span><span class="n">p</span><span class="o">&amp;&amp;</span><span class="n">z</span><span class="o">==</span><span class="mi">0</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="nf">printf</span><span class="p">(</span><span class="s">&#34;1.000000000000</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">        <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">x</span><span class="o">-</span><span class="n">p</span><span class="o">&lt;</span><span class="mi">0</span><span class="o">||</span><span class="n">y</span><span class="o">-</span><span class="n">q</span><span class="o">&lt;</span><span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
</span></span><span class="line"><span class="cl">        <span class="nf">printf</span><span class="p">(</span><span class="s">&#34;0.000000000000</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">        <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="n">x</span><span class="o">=</span><span class="n">x</span><span class="o">-</span><span class="n">p</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="nf">printf</span><span class="p">(</span><span class="s">&#34;%0.12f&#34;</span><span class="p">,</span><span class="n">c</span><span class="p">[</span><span class="n">z</span><span class="p">][</span><span class="n">x</span><span class="p">]</span><span class="o">*</span><span class="mf">1.0</span><span class="o">/</span><span class="p">(</span><span class="mi">2</span><span class="o">&lt;&lt;</span><span class="p">(</span><span class="n">z</span><span class="o">-</span><span class="mi">1</span><span class="p">)));</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div><p>几分钟写完后面的代码，心中一万头草泥马在奔腾。</p>
]]></description></item><item><title>The equation-SGU106（扩展欧几里得）</title><link>https://lruihao.cn/posts/euclid/</link><pubDate>Fri, 10 Aug 2018 10:32:39 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/euclid/</guid><description><![CDATA[<h3 id="题意">题意：</h3>
<p>给出 a,b,c,x1,x2,y1,y2，求满足 ax+by+c=0，且 x∈[x1,x2],y∈[y1,y2] 的整数解个数。</p>
<h3 id="分析">分析：</h3>
<p>对于解二元一次不定方程，容易想到利用扩展欧几里得求出一组可行解后找到通解，下面来介绍一下欧几里得以及扩展欧几里得。</p>
<h4 id="欧几里得">欧几里得：</h4>
<p>又名辗转相除法，是用来计算两个数的最大公约数，其中就是利用 gcd(a,b)=gcd(b,a mod b) 来求解。下证 gcd(a,b)=gcd(b,a mod b) 的正确性：</p>
<p>设 a,b 的一个公约数为 d</p>
<p>设 a mod b=r，则 a=kb+r(k 为整数），r=a-kb</p>
<p>因为 d|a,d|b</p>
<p>所以 d|a-kb, 即 d|r，而 r=a mod b</p>
<p>所以 d 为 b,a mod b 的公约数</p>
<p>又因为 d 也为 a,b 的公约数，所以（a,b) 和 (b,a mod b) 的公约数一样，所以最大公约数必然一样，得证。</p>
<p>代码描述：</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt">1
</span><span class="lnt">2
</span><span class="lnt">3
</span><span class="lnt">4
</span><span class="lnt">5
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">gcd</span><span class="p">(</span><span class="kt">int</span> <span class="n">a</span><span class="p">,</span><span class="kt">int</span> <span class="n">b</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span> <span class="p">(</span><span class="n">b</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span> <span class="k">return</span> <span class="n">a</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="nf">gcd</span><span class="p">(</span><span class="n">b</span><span class="p">,</span><span class="n">a</span><span class="o">%</span><span class="n">b</span><span class="p">);</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div><h4 id="扩展欧几里得">扩展欧几里得</h4>
<p>顾名思义，为上述欧几里得算法的扩展。欧几里得是用来求 a,b 的最大公约数，那么扩展欧几里得不仅能求出 a,b 的最大公约数，还能求出满足 ax+by=gcd(a,b) 的一组可行解。<br>
求解过程中，扩展欧几里得比欧几里得多了一个赋值过程，具体证明如下：</p>
<p>设 ax1+by1=gcd(a,b),bx2+(a mod b)y2=gcd(b,a mod b)</p>
<p>因为由欧几里得算法可知，gcd(a,b)=gcd(b,a mod b)</p>
<p>所以 ax1+by1=bx2+(a mod b)y2</p>
<p>因为<code>a mod b=a-(a div b)*b（div 为整除</code></p>
<p>所以有<code>ax1+by1=bx2+(a-(a div b)*b)y2</code></p>
<p>将右边移项，展开得：</p>
<div class="highlight" id="id-2"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt">1
</span><span class="lnt">2
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-fallback" data-lang="fallback"><span class="line"><span class="cl">ax1+by1=ay2+bx2-(a div b)*b*y2
</span></span><span class="line"><span class="cl">       =ay2+b[x2-(a div b)]y2</span></span></code></pre></td></tr></table>
</div>
</div><p>所以可得：
<code>x1=y2</code>
<code>y1=x2-(a div b)*y2</code></p>
<p>将得到的的 x1,y1 递归操作求解 x2,y2，如此循环往复，将会像欧几里得一样得到 b=0 的情况，此时递归结束，返回 x=1,y=0，回溯得解。</p>
<p>代码描述：</p>
<p>此函数返回的是 a,b 的最大公约数，同时也求解出满足 ax+by=gcd(a,b) 的一组可行的 (x,y)</p>
<div class="highlight" id="id-3"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt">1
</span><span class="lnt">2
</span><span class="lnt">3
</span><span class="lnt">4
</span><span class="lnt">5
</span><span class="lnt">6
</span><span class="lnt">7
</span><span class="lnt">8
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">exgcd</span><span class="p">(</span><span class="kt">int</span> <span class="n">a</span><span class="p">,</span><span class="kt">int</span> <span class="n">b</span><span class="p">,</span><span class="kt">int</span> <span class="o">&amp;</span><span class="n">x</span><span class="p">,</span><span class="kt">int</span> <span class="o">&amp;</span><span class="n">y</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span> <span class="p">(</span><span class="n">b</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span> <span class="p">{</span><span class="n">x</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">y</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="k">return</span> <span class="n">a</span><span class="p">;}</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">t</span><span class="o">=</span><span class="nf">exgcd</span><span class="p">(</span><span class="n">b</span><span class="p">,</span><span class="n">a</span><span class="o">%</span><span class="n">b</span><span class="p">,</span><span class="n">x</span><span class="p">,</span><span class="n">y</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">x0</span><span class="o">=</span><span class="n">x</span><span class="p">,</span><span class="n">y0</span><span class="o">=</span><span class="n">y</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">x</span><span class="o">=</span><span class="n">y0</span><span class="p">;</span><span class="n">y</span><span class="o">=</span><span class="n">x0</span><span class="o">-</span><span class="p">(</span><span class="n">a</span><span class="o">/</span><span class="n">b</span><span class="p">)</span><span class="o">*</span><span class="n">y0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div><h4 id="关于求解二元一次不定方程-axbyc">关于求解二元一次不定方程 ax+by=c</h4>
<p>首先，如果 c 不是 gcd(a,b) 的倍数，方程显然无解。</p>
<p>扩展欧几里得求解的是 ax+by=gcd(a,b)=1 的可行解，但是题目中并没有说 c 与 a,b 互质之类的条件，所以需要在开始时两边同时除以 gcd(a,b)。</p>
<p>设 d=gcd(a,b)</p>
<p>设 a&rsquo;=a/d,b&rsquo;=b/d,c&rsquo;=c/d,</p>
<p>则下面需要求解 a&rsquo;x+b&rsquo;y=c&rsquo;的整数解，而 gcd(a&rsquo;,b&rsquo;)=1，</p>
<p>则我们只需求 a&rsquo;x+b&rsquo;y=1 的可行解</p>
<p>直接使用扩展欧几里得，得到 (x&rsquo;,y&rsquo;), 则最终解为<code>x'*c',y'*c'</code>设为 (x0,y0)。</p>
<p>现在得到了一组可行解，但是如何得到通解呢？</p>
<p>将 (x0,y0) 代入 ax+by=c，则有</p>
<p><code>a*(x0)+b*(y0)=c</code></p>
<p>通过拆添项，可有：</p>
<div class="highlight" id="id-4"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt">1
</span><span class="lnt">2
</span><span class="lnt">3
</span><span class="lnt">4
</span><span class="lnt">5
</span><span class="lnt">6
</span><span class="lnt">7
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-fallback" data-lang="fallback"><span class="line"><span class="cl">a*(x0+1*b)+b*(y0-1*a)=c
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">a*(x0+2*b)+b*(y0-2*a)=c
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">a*(x0+3*b)+b*(y0-3*a)=c
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">……</span></span></code></pre></td></tr></table>
</div>
</div><p><code>a*(x0+k*b)+b*(y0-k*a)=c (k∈Z)</code></p>
<p>至此，我们得到了通解的方程</p>
<p><code>x=x0+k*b</code>
<code>y=y0-k*a (k∈Z)</code></p>
<p>这样，所有满足 ax+by=c 的可行解都可求出。</p>
<h3 id="具体实现">具体实现</h3>
<p>有了主体算法，下面要谈到具体实现了。</p>
<h4 id="先处理一下无解的情况">先处理一下无解的情况：</h4>
<ol>
<li>
<p>当 a=0 并且 b=0，而 c≠0 时，显然无解；<br>
当 a=0,b=0，而 c=0 时，[x1,x2],[y1,y2] 都为可行解，根据乘法原理，可行解的个数为<code>(x2-x1+1)*(y2-y1+1)</code>;</p>
</li>
<li>
<p>当 a=0 b≠0 时：<br>
此时即为求解 by=c，则 y=c/b，<br>
如果 c/b 不是整数或 c/b 不在 [y1,y2] 的范围内，无解<br>
否则 [x1,x2] 内全部整数都为可行解。</p>
</li>
<li>
<p>当 b=0,a≠0 时，同上。</p>
</li>
<li>
<p>若 c 不是 gcd(a,b) 的个数，方程显然无解。</p>
</li>
</ol>
<h4 id="处理完了一些繁琐的细节后下面是具体的求解过程">处理完了一些繁琐的细节后，下面是具体的求解过程：</h4>
<ol>
<li>
<p>扩展欧几里得求解的是 ax+by=c，而本题是 ax+by+c=0，需将 c 移项。</p>
</li>
<li>
<p>对于本道题，首先要注意的是，对于负数的模运算在此算法中无法得到正确解，所以要处理一下 a,b,c 的正负情况。
如果 a 为负数，只需将 a 取相反数后，再处理一下 x∈[x1,x2] 的范围。当 a 取了相反数，相当于把 x 也取反，则需要把 x 的范围由 [x1,x2] 转变成 [-x2,-x1], 类似于把数轴反了过来。b 同理。</p>
</li>
<li>
<p>利用扩展欧几里得解二元一次不定方程，得到一组可行解 (x0,y0)。</p>
</li>
<li>
<p>因为题目中对 x,y 有条件约束，而有 x=x0+kb,y=y0-kb，我们可以求出满足 x∈[x1,x2],y∈[y1,y2] 的 k 的取值范围，
即为求解 x1&lt;=x0+kb&lt;=x2,y1&lt;=y0-kb&lt;=y2 的整数 k 的个数
但是在求解这两个一次函数的过程中，会有除不尽的现象，该如何取整呢？</p>
</li>
</ol>
<p>举个例子</p>
<p>当出现 2.5&lt;=k&lt;=5.5 时，我们需要的可行的 k 为 3,4,5，所以需要将 2.5 向上取整得到 3，5.5 向下取整得到 5，即为 3&lt;=k&lt;=5；</p>
<p>当出现-5.5&lt;=&lt;=-2.5 时，我们需要的可行的 k 为-5,-4,-3, 所以需要将-5.5 向上取整得到-5,-2.5 向下取整得到-3，即为-5&lt;=k&lt;=-3；</p>
<p>正负数的情况都已经考虑完全了，可以得到取整的结论：上界下取整，下界上取整。</p>
<p>最后，将得到的两个范围取交集，得到 [l,r]，则最终答案为 r-l+1。</p>
<p>这样，本题就可以完美解决了。</p>
<div class="highlight" id="id-5"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span><span class="lnt">33
</span><span class="lnt">34
</span><span class="lnt">35
</span><span class="lnt">36
</span><span class="lnt">37
</span><span class="lnt">38
</span><span class="lnt">39
</span><span class="lnt">40
</span><span class="lnt">41
</span><span class="lnt">42
</span><span class="lnt">43
</span><span class="lnt">44
</span><span class="lnt">45
</span><span class="lnt">46
</span><span class="lnt">47
</span><span class="lnt">48
</span><span class="lnt">49
</span><span class="lnt">50
</span><span class="lnt">51
</span><span class="lnt">52
</span><span class="lnt">53
</span><span class="lnt">54
</span><span class="lnt">55
</span><span class="lnt">56
</span><span class="lnt">57
</span><span class="lnt">58
</span><span class="lnt">59
</span><span class="lnt">60
</span><span class="lnt">61
</span><span class="lnt">62
</span><span class="lnt">63
</span><span class="lnt">64
</span><span class="lnt">65
</span><span class="lnt">66
</span><span class="lnt">67
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="c1">// BY Rinyo
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>
</span></span><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;cstdio&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;cmath&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="kt">long</span> <span class="kt">long</span> <span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">,</span><span class="n">c</span><span class="p">,</span><span class="n">x1</span><span class="p">,</span><span class="n">x2</span><span class="p">,</span><span class="n">yy1</span><span class="p">,</span><span class="n">y2</span><span class="p">,</span><span class="n">x0</span><span class="p">,</span><span class="n">yy0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="kr">inline</span> <span class="kt">long</span> <span class="kt">long</span> <span class="nf">cmin</span><span class="p">(</span><span class="k">const</span> <span class="kt">long</span> <span class="kt">long</span> <span class="o">&amp;</span><span class="n">x</span><span class="p">,</span><span class="k">const</span> <span class="kt">long</span> <span class="kt">long</span> <span class="o">&amp;</span><span class="n">y</span><span class="p">)</span> <span class="p">{</span><span class="k">return</span> <span class="n">x</span><span class="o">&lt;</span><span class="n">y</span><span class="o">?</span><span class="nl">x</span><span class="p">:</span><span class="n">y</span><span class="p">;}</span>
</span></span><span class="line"><span class="cl"><span class="kr">inline</span> <span class="kt">long</span> <span class="kt">long</span> <span class="nf">cmax</span><span class="p">(</span><span class="k">const</span> <span class="kt">long</span> <span class="kt">long</span> <span class="o">&amp;</span><span class="n">x</span><span class="p">,</span><span class="k">const</span> <span class="kt">long</span> <span class="kt">long</span> <span class="o">&amp;</span><span class="n">y</span><span class="p">)</span> <span class="p">{</span><span class="k">return</span> <span class="n">x</span><span class="o">&gt;</span><span class="n">y</span><span class="o">?</span><span class="nl">x</span><span class="p">:</span><span class="n">y</span><span class="p">;}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">long</span> <span class="kt">long</span> <span class="nf">gcd</span><span class="p">(</span><span class="kt">long</span> <span class="kt">long</span> <span class="n">a</span><span class="p">,</span><span class="kt">long</span> <span class="kt">long</span> <span class="n">b</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span> <span class="p">(</span><span class="n">b</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span> <span class="k">return</span> <span class="n">a</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">gcd</span><span class="p">(</span><span class="n">b</span><span class="p">,</span><span class="n">a</span> <span class="o">%</span> <span class="n">b</span><span class="p">);</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl"><span class="kt">void</span> <span class="nf">exgcd</span><span class="p">(</span><span class="kt">long</span> <span class="kt">long</span> <span class="n">a</span><span class="p">,</span><span class="kt">long</span> <span class="kt">long</span> <span class="n">b</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span> <span class="p">(</span><span class="n">b</span><span class="o">==</span><span class="mi">0</span><span class="p">){</span><span class="n">x0</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">yy0</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="k">return</span><span class="p">;}</span>
</span></span><span class="line"><span class="cl">    <span class="n">exgcd</span><span class="p">(</span><span class="n">b</span><span class="p">,</span><span class="n">a</span><span class="o">%</span><span class="n">b</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="kt">long</span> <span class="kt">long</span> <span class="n">t</span><span class="o">=</span><span class="n">x0</span><span class="p">;</span><span class="n">x0</span><span class="o">=</span><span class="n">yy0</span><span class="p">;</span><span class="n">yy0</span><span class="o">=</span><span class="n">t</span><span class="o">-</span><span class="n">a</span><span class="o">/</span><span class="n">b</span><span class="o">*</span><span class="n">yy0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">()</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%I64d%I64d%I64d%I64d%I64d%I64d%I64d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">a</span><span class="p">,</span><span class="o">&amp;</span><span class="n">b</span><span class="p">,</span><span class="o">&amp;</span><span class="n">c</span><span class="p">,</span><span class="o">&amp;</span><span class="n">x1</span><span class="p">,</span><span class="o">&amp;</span><span class="n">x2</span><span class="p">,</span><span class="o">&amp;</span><span class="n">yy1</span><span class="p">,</span><span class="o">&amp;</span><span class="n">y2</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="n">c</span><span class="o">=-</span><span class="n">c</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span> <span class="p">(</span><span class="n">c</span><span class="o">&lt;</span><span class="mi">0</span><span class="p">)</span> <span class="p">{</span><span class="n">a</span><span class="o">=-</span><span class="n">a</span><span class="p">;</span><span class="n">b</span><span class="o">=-</span><span class="n">b</span><span class="p">;</span><span class="n">c</span><span class="o">=-</span><span class="n">c</span><span class="p">;}</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span> <span class="p">(</span><span class="n">a</span><span class="o">&lt;</span><span class="mi">0</span><span class="p">)</span> <span class="p">{</span><span class="n">a</span><span class="o">=-</span><span class="n">a</span><span class="p">;</span><span class="kt">long</span> <span class="kt">long</span> <span class="n">t</span><span class="o">=</span><span class="n">x1</span><span class="p">;</span><span class="n">x1</span><span class="o">=-</span><span class="n">x2</span><span class="p">;</span><span class="n">x2</span><span class="o">=-</span><span class="n">t</span><span class="p">;}</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span> <span class="p">(</span><span class="n">b</span><span class="o">&lt;</span><span class="mi">0</span><span class="p">)</span> <span class="p">{</span><span class="n">b</span><span class="o">=-</span><span class="n">b</span><span class="p">;</span><span class="kt">long</span> <span class="kt">long</span> <span class="n">t</span><span class="o">=</span><span class="n">yy1</span><span class="p">;</span><span class="n">yy1</span><span class="o">=-</span><span class="n">y2</span><span class="p">;</span><span class="n">y2</span><span class="o">=-</span><span class="n">t</span><span class="p">;}</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span> <span class="p">(</span><span class="n">a</span><span class="o">==</span><span class="mi">0</span> <span class="o">&amp;&amp;</span> <span class="n">b</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">    <span class="p">{</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span> <span class="p">(</span><span class="n">c</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="p">{</span>
</span></span><span class="line"><span class="cl">            <span class="n">printf</span><span class="p">(</span><span class="s">&#34;%I64d&#34;</span><span class="p">,(</span><span class="n">x2</span><span class="o">-</span><span class="n">x1</span><span class="o">+</span><span class="mi">1</span><span class="p">)</span><span class="o">*</span><span class="p">(</span><span class="n">y2</span><span class="o">-</span><span class="n">yy1</span><span class="o">+</span><span class="mi">1</span><span class="p">));</span>
</span></span><span class="line"><span class="cl">            <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;0&#34;</span><span class="p">);</span><span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">else</span> <span class="k">if</span> <span class="p">(</span><span class="n">a</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">    <span class="p">{</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span> <span class="p">(</span><span class="n">c</span> <span class="o">%</span><span class="n">b</span> <span class="o">==</span><span class="mi">0</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span> <span class="p">(</span><span class="n">c</span><span class="o">/</span><span class="n">b</span><span class="o">&lt;=</span><span class="n">y2</span> <span class="o">&amp;&amp;</span> <span class="n">c</span><span class="o">/</span><span class="n">b</span><span class="o">&gt;=</span><span class="n">yy1</span><span class="p">)</span> <span class="p">{</span><span class="n">printf</span><span class="p">(</span><span class="s">&#34;%I64d&#34;</span><span class="p">,</span><span class="n">x2</span><span class="o">-</span><span class="n">x1</span><span class="o">+</span><span class="mi">1</span><span class="p">);</span><span class="k">return</span> <span class="mi">0</span><span class="p">;}</span>
</span></span><span class="line"><span class="cl">        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;0&#34;</span><span class="p">);</span><span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">else</span> <span class="k">if</span> <span class="p">(</span><span class="n">b</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">    <span class="p">{</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span> <span class="p">(</span><span class="n">c</span><span class="o">%</span><span class="n">a</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span> <span class="p">(</span><span class="n">c</span><span class="o">/</span><span class="n">a</span><span class="o">&lt;=</span><span class="n">x2</span> <span class="o">&amp;&amp;</span> <span class="n">c</span><span class="o">/</span><span class="n">a</span><span class="o">&gt;=</span><span class="n">x1</span><span class="p">)</span> <span class="p">{</span><span class="n">printf</span><span class="p">(</span><span class="s">&#34;%I64d&#34;</span><span class="p">,</span><span class="n">y2</span><span class="o">-</span><span class="n">yy1</span><span class="o">+</span><span class="mi">1</span><span class="p">);</span><span class="k">return</span> <span class="mi">0</span><span class="p">;}</span>
</span></span><span class="line"><span class="cl">        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;0&#34;</span><span class="p">);</span><span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="kt">long</span> <span class="kt">long</span> <span class="n">d</span><span class="o">=</span><span class="n">gcd</span><span class="p">(</span><span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span> <span class="p">(</span><span class="n">c</span><span class="o">%</span><span class="n">d</span><span class="o">!=</span><span class="mi">0</span><span class="p">){</span><span class="n">printf</span><span class="p">(</span><span class="s">&#34;0&#34;</span><span class="p">);</span><span class="k">return</span> <span class="mi">0</span><span class="p">;}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="n">a</span><span class="o">=</span><span class="n">a</span><span class="o">/</span><span class="n">d</span><span class="p">;</span><span class="n">b</span><span class="o">=</span><span class="n">b</span><span class="o">/</span><span class="n">d</span><span class="p">;</span><span class="n">c</span><span class="o">=</span><span class="n">c</span><span class="o">/</span><span class="n">d</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">exgcd</span><span class="p">(</span><span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="n">x0</span><span class="o">=</span><span class="n">x0</span><span class="o">*</span><span class="n">c</span><span class="p">;</span><span class="n">yy0</span><span class="o">=</span><span class="n">yy0</span><span class="o">*</span><span class="n">c</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="kt">double</span> <span class="n">tx2</span><span class="o">=</span><span class="n">x2</span><span class="p">,</span><span class="n">tx1</span><span class="o">=</span><span class="n">x1</span><span class="p">,</span><span class="n">tx0</span><span class="o">=</span><span class="n">x0</span><span class="p">,</span><span class="n">ta</span><span class="o">=</span><span class="n">a</span><span class="p">,</span><span class="n">tb</span><span class="o">=</span><span class="n">b</span><span class="p">,</span><span class="n">tc</span><span class="o">=</span><span class="n">c</span><span class="p">,</span><span class="n">ty1</span><span class="o">=</span><span class="n">yy1</span><span class="p">,</span><span class="n">ty2</span><span class="o">=</span><span class="n">y2</span><span class="p">,</span><span class="n">ty0</span><span class="o">=</span><span class="n">yy0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">long</span> <span class="kt">long</span> <span class="n">down1</span><span class="o">=</span><span class="n">floor</span><span class="p">(((</span><span class="n">tx2</span><span class="o">-</span><span class="n">tx0</span><span class="p">)</span><span class="o">/</span><span class="n">tb</span><span class="p">)),</span><span class="n">down2</span><span class="o">=</span><span class="n">floor</span><span class="p">(((</span><span class="n">ty0</span><span class="o">-</span><span class="n">ty1</span><span class="p">)</span><span class="o">/</span><span class="n">ta</span><span class="p">));</span>
</span></span><span class="line"><span class="cl">    <span class="kt">long</span> <span class="kt">long</span> <span class="n">r</span><span class="o">=</span><span class="n">cmin</span><span class="p">(</span><span class="n">down1</span><span class="p">,</span><span class="n">down2</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="kt">long</span> <span class="kt">long</span> <span class="n">up1</span><span class="o">=</span><span class="n">ceil</span><span class="p">(((</span><span class="n">tx1</span><span class="o">-</span><span class="n">tx0</span><span class="p">)</span><span class="o">/</span><span class="n">tb</span><span class="p">)),</span><span class="n">up2</span><span class="o">=</span><span class="n">ceil</span><span class="p">(((</span><span class="n">ty0</span><span class="o">-</span><span class="n">ty2</span><span class="p">)</span><span class="o">/</span><span class="n">ta</span><span class="p">));</span>
</span></span><span class="line"><span class="cl">    <span class="kt">long</span> <span class="kt">long</span> <span class="n">l</span><span class="o">=</span><span class="n">cmax</span><span class="p">(</span><span class="n">up1</span><span class="p">,</span><span class="n">up2</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span> <span class="p">(</span><span class="n">r</span><span class="o">&lt;</span><span class="n">l</span><span class="p">)</span> <span class="n">printf</span><span class="p">(</span><span class="s">&#34;0&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="k">else</span> <span class="n">printf</span><span class="p">(</span><span class="s">&#34;%I64d&#34;</span><span class="p">,</span><span class="n">r</span><span class="o">-</span><span class="n">l</span><span class="o">+</span><span class="mi">1</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div><p>扩展欧几里得模板</p>
<div class="highlight" id="id-6"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;iostream&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="n">using</span> <span class="n">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">exgcd</span><span class="p">(</span><span class="kt">int</span> <span class="n">a</span><span class="p">,</span><span class="kt">int</span> <span class="n">b</span><span class="p">,</span><span class="kt">int</span> <span class="o">&amp;</span><span class="n">x</span><span class="p">,</span><span class="kt">int</span> <span class="o">&amp;</span><span class="n">y</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">     <span class="k">if</span><span class="p">(</span><span class="n">b</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">    <span class="p">{</span>
</span></span><span class="line"><span class="cl">        <span class="n">x</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">y</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">return</span> <span class="n">a</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">gcd</span><span class="o">=</span><span class="nf">exgcd</span><span class="p">(</span><span class="n">b</span><span class="p">,</span><span class="n">a</span><span class="o">%</span><span class="n">b</span><span class="p">,</span><span class="n">x</span><span class="p">,</span><span class="n">y</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">x2</span><span class="o">=</span><span class="n">x</span><span class="p">,</span><span class="n">y2</span><span class="o">=</span><span class="n">y</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">x</span><span class="o">=</span><span class="n">y2</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">y</span><span class="o">=</span><span class="n">x2</span><span class="o">-</span><span class="p">(</span><span class="n">a</span><span class="o">/</span><span class="n">b</span><span class="p">)</span><span class="o">*</span><span class="n">y2</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">gcd</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">()</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">x</span><span class="p">,</span><span class="n">y</span><span class="p">,</span><span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="n">cout</span><span class="o">&lt;&lt;</span><span class="s">&#34;请输入 a 和 b:&#34;</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">a</span><span class="o">&gt;&gt;</span><span class="n">b</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="n">cout</span><span class="o">&lt;&lt;</span><span class="s">&#34;a 和 b 的最大公约数：&#34;</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="n">cout</span><span class="o">&lt;&lt;</span><span class="nf">exgcd</span><span class="p">(</span><span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">,</span><span class="n">x</span><span class="p">,</span><span class="n">y</span><span class="p">)</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="n">cout</span><span class="o">&lt;&lt;</span><span class="s">&#34;ax+by=gcd(a,b) 的一组解是：&#34;</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">x</span><span class="o">&lt;&lt;</span><span class="s">&#34; &#34;</span><span class="o">&lt;&lt;</span><span class="n">y</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>Codeforces Round 502(Div.1 + Div.2)</title><link>https://lruihao.cn/posts/cfcontest1017/</link><pubDate>Thu, 09 Aug 2018 10:48:00 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/cfcontest1017/</guid><description><![CDATA[<h3 id="a-the-rankhttpscodeforcescomcontest1017problema"><a href="https://codeforces.com/contest/1017/problem/A"target="_blank" rel="external nofollow noopener noreferrer">A. The Rank<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></h3>
<p>题目大意：<br>
给出 n 个学生的成绩，Thomas Smith 的成绩是第一行，然后要按总成绩进行排序，总分相同的按编号从小到大排；<br>
开始看还以为要写 sort 的 cmp 函数进行多条件排序，敲完才发现其实只要按总分就可以了，因为托马斯的 id 是一，必然会排在前面。</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="n">using</span> <span class="n">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">a</span><span class="p">[</span><span class="mi">4</span><span class="p">],</span><span class="n">sum</span><span class="p">[</span><span class="mi">1005</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">n</span><span class="p">,</span><span class="n">s</span><span class="p">,</span><span class="n">f1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">n</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">j</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">j</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">j</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">s</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="mi">4</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">a</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">            <span class="n">s</span><span class="o">+=</span><span class="n">a</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="n">sum</span><span class="p">[</span><span class="n">j</span><span class="p">]</span><span class="o">=</span><span class="n">s</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">j</span><span class="o">==</span><span class="mi">1</span><span class="p">)</span> <span class="n">f1</span><span class="o">=</span><span class="n">s</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="nf">sort</span><span class="p">(</span><span class="n">sum</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="n">sum</span><span class="o">+</span><span class="n">n</span><span class="o">+</span><span class="mi">1</span><span class="p">,</span><span class="n">greater</span><span class="o">&lt;</span><span class="kt">int</span><span class="o">&gt;</span><span class="p">());</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">sum</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">==</span><span class="n">f1</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">i</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="k">break</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div><h3 id="b-the-bitshttpscodeforcescomcontest1017problemb"><a href="https://codeforces.com/contest/1017/problem/B"target="_blank" rel="external nofollow noopener noreferrer">B. The Bits<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></h3>
<p>题目大意：<br>
先给出二进制数的长度，然后输入两个二进制数 a,b，问交换 a 中的某些位数的数，使得 a|b（按位或）的结果不同，求有多少种不同的或值。</p>
<table>
<thead>
<tr>
<th style="text-align:center">a,b 上下对应的情况：a/b</th>
<th style="text-align:center">个数</th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align:center">1/0</td>
<td style="text-align:center">m</td>
</tr>
<tr>
<td style="text-align:center">0/0</td>
<td style="text-align:center">n</td>
</tr>
<tr>
<td style="text-align:center">1/1</td>
<td style="text-align:center">x</td>
</tr>
<tr>
<td style="text-align:center">0/1</td>
<td style="text-align:center">y</td>
</tr>
</tbody>
</table>
<p>用组合数学的思想来想：<br>
只要看 b 为 0 的位就行了，如果 0/0,a 只能换 1 的位置，为了避免重复，所以这里总数为<code>n*x</code>,<br>
再考虑 1/0 的情况，只能和 0 的位置换，这是后可以把 0/0 没算的都算上，所以总数<code>m*(n+y)</code><br>
<strong>所以最后总数为<code>sum=n*x+m*(n+y)</code></strong></p>
<div class="highlight" id="id-2"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="n">using</span> <span class="n">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">long</span> <span class="kt">long</span> <span class="n">n</span><span class="p">,</span><span class="n">m</span><span class="p">,</span><span class="n">x</span><span class="p">,</span><span class="n">y</span><span class="p">,</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">n</span><span class="o">=</span><span class="n">m</span><span class="o">=</span><span class="n">x</span><span class="o">=</span><span class="n">y</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">char</span> <span class="n">a</span><span class="p">[</span><span class="mi">100005</span><span class="p">],</span><span class="n">b</span><span class="p">[</span><span class="mi">100005</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">a</span><span class="o">&gt;&gt;</span><span class="n">b</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">t</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="kt">int</span> <span class="n">p</span><span class="o">=</span><span class="n">a</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">-</span><span class="sc">&#39;0&#39;</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="kt">int</span> <span class="n">q</span><span class="o">=</span><span class="n">b</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">-</span><span class="sc">&#39;0&#39;</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">p</span><span class="o">==</span><span class="mi">0</span><span class="o">&amp;&amp;</span><span class="n">q</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span> <span class="n">n</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">p</span><span class="o">==</span><span class="mi">1</span><span class="o">&amp;&amp;</span><span class="n">q</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span> <span class="n">m</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">p</span><span class="o">==</span><span class="mi">1</span><span class="o">&amp;&amp;</span><span class="n">q</span><span class="o">==</span><span class="mi">1</span><span class="p">)</span> <span class="n">x</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">p</span><span class="o">==</span><span class="mi">0</span><span class="o">&amp;&amp;</span><span class="n">q</span><span class="o">==</span><span class="mi">1</span><span class="p">)</span> <span class="n">y</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="kt">long</span> <span class="kt">long</span> <span class="n">sum</span><span class="o">=</span><span class="n">n</span><span class="o">*</span><span class="n">x</span><span class="o">+</span><span class="n">m</span><span class="o">*</span><span class="p">(</span><span class="n">y</span><span class="o">+</span><span class="n">n</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">sum</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>Heavy Transportation-poj1797(dijkstra 或最大生成树）</title><link>https://lruihao.cn/posts/poj1797/</link><pubDate>Mon, 06 Aug 2018 09:42:11 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/poj1797/</guid><description><![CDATA[<p>题目链接](<a href="http://poj.org/problem?id=1797"target="_blank" rel="external nofollow noopener noreferrer">http://poj.org/problem?id=1797<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a>)<br>
大意：<br>
要从城市 1 到城市 N 运送货物，有 M 条道路，每条道路都有它的最大载重量，问从城市 1 到城市 N 运送最多的重量是多少。<br>
其实题意很简单，就是找一条 1&ndash;&gt;N 的路径，在不超过每条路径的最大载重量的情况下，使得运送的货物最多。一条路径上的最大载重量为这个路径上权值最小的边；
</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span><span class="lnt">33
</span><span class="lnt">34
</span><span class="lnt">35
</span><span class="lnt">36
</span><span class="lnt">37
</span><span class="lnt">38
</span><span class="lnt">39
</span><span class="lnt">40
</span><span class="lnt">41
</span><span class="lnt">42
</span><span class="lnt">43
</span><span class="lnt">44
</span><span class="lnt">45
</span><span class="lnt">46
</span><span class="lnt">47
</span><span class="lnt">48
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="c1">//dijkstra
</span></span></span><span class="line"><span class="cl"><span class="c1"></span><span class="cp">#include</span><span class="cpf">&lt;iostream&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;cstdio&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp">#define min(a,b) (a&lt;b?a:b)
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">n</span><span class="p">,</span><span class="n">m</span><span class="p">,</span><span class="n">v</span><span class="p">[</span><span class="mi">1010</span><span class="p">],</span><span class="n">maps</span><span class="p">[</span><span class="mi">1010</span><span class="p">][</span><span class="mi">1010</span><span class="p">],</span><span class="n">d</span><span class="p">[</span><span class="mi">1010</span><span class="p">];</span><span class="c1">//此时 d 表示 1 到每一个点的能通过的最大的重量
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">dijkstra</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">i</span><span class="p">,</span><span class="n">j</span><span class="p">,</span><span class="n">k</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">v</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">d</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">=</span><span class="n">maps</span><span class="p">[</span><span class="mi">1</span><span class="p">][</span><span class="n">i</span><span class="p">];</span><span class="c1">//这个时候 d 不代表最短路径，而是从 1 到 n 的最大承载量
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span><span class="c1">//n 个点
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>        <span class="kt">int</span> <span class="n">f</span><span class="o">=-</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">j</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">j</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">j</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span><span class="p">(</span><span class="o">!</span><span class="n">v</span><span class="p">[</span><span class="n">j</span><span class="p">]</span><span class="o">&amp;&amp;</span><span class="n">d</span><span class="p">[</span><span class="n">j</span><span class="p">]</span><span class="o">&gt;</span><span class="n">f</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">                <span class="n">f</span><span class="o">=</span><span class="n">d</span><span class="p">[</span><span class="n">j</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">                <span class="n">k</span><span class="o">=</span><span class="n">j</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="n">v</span><span class="p">[</span><span class="n">k</span><span class="p">]</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">j</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">j</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">j</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span><span class="p">(</span><span class="o">!</span><span class="n">v</span><span class="p">[</span><span class="n">j</span><span class="p">]</span><span class="o">&amp;&amp;</span><span class="n">d</span><span class="p">[</span><span class="n">j</span><span class="p">]</span><span class="o">&lt;</span><span class="n">min</span><span class="p">(</span><span class="n">d</span><span class="p">[</span><span class="n">k</span><span class="p">],</span><span class="n">maps</span><span class="p">[</span><span class="n">k</span><span class="p">][</span><span class="n">j</span><span class="p">]))</span><span class="c1">//更新说明见图解
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>                <span class="n">d</span><span class="p">[</span><span class="n">j</span><span class="p">]</span><span class="o">=</span><span class="n">min</span><span class="p">(</span><span class="n">d</span><span class="p">[</span><span class="n">k</span><span class="p">],</span><span class="n">maps</span><span class="p">[</span><span class="n">k</span><span class="p">][</span><span class="n">j</span><span class="p">]);</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">d</span><span class="p">[</span><span class="n">n</span><span class="p">];</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">ans</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">,</span><span class="n">w</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">T</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">T</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">T</span><span class="o">--</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">			<span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">j</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">j</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">j</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">				<span class="n">maps</span><span class="p">[</span><span class="n">i</span><span class="p">][</span><span class="n">j</span><span class="p">]</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">n</span><span class="p">,</span><span class="o">&amp;</span><span class="n">m</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">m</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d%d%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">a</span><span class="p">,</span><span class="o">&amp;</span><span class="n">b</span><span class="p">,</span><span class="o">&amp;</span><span class="n">w</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">            <span class="n">maps</span><span class="p">[</span><span class="n">a</span><span class="p">][</span><span class="n">b</span><span class="p">]</span><span class="o">=</span><span class="n">maps</span><span class="p">[</span><span class="n">b</span><span class="p">][</span><span class="n">a</span><span class="p">]</span><span class="o">=</span><span class="n">w</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;Scenario #%d:</span><span class="se">\n</span><span class="s">%d</span><span class="se">\n\n</span><span class="s">&#34;</span><span class="p">,</span><span class="n">ans</span><span class="o">++</span><span class="p">,</span><span class="n">dijkstra</span><span class="p">());</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>Til the Cows Come Home-poj2387(dijkstra 判断重边）</title><link>https://lruihao.cn/posts/poj2387/</link><pubDate>Fri, 03 Aug 2018 21:40:33 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/poj2387/</guid><description><![CDATA[<p><a href="http://poj.org/problem?id=2387"target="_blank" rel="external nofollow noopener noreferrer">题目链接<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></p>
<p>题目大意：<br>
说的是，一只奶牛位于 N 号节点，输入 N 个节点和 T 对双向的边，求出由 N 到 1 的最短的距离，其实就是问的单源最短路问题。</p>
<p>两个点可能有多条路，选择最短的。</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span><span class="lnt">33
</span><span class="lnt">34
</span><span class="lnt">35
</span><span class="lnt">36
</span><span class="lnt">37
</span><span class="lnt">38
</span><span class="lnt">39
</span><span class="lnt">40
</span><span class="lnt">41
</span><span class="lnt">42
</span><span class="lnt">43
</span><span class="lnt">44
</span><span class="lnt">45
</span><span class="lnt">46
</span><span class="lnt">47
</span><span class="lnt">48
</span><span class="lnt">49
</span><span class="lnt">50
</span><span class="lnt">51
</span><span class="lnt">52
</span><span class="lnt">53
</span><span class="lnt">54
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;stdio.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;string.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;algorithm&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="k">const</span> <span class="kt">int</span> <span class="n">INF</span><span class="o">=</span><span class="mi">99999999</span><span class="p">;</span>                    <span class="c1">//设为无穷大
</span></span></span><span class="line"><span class="cl"><span class="c1"></span><span class="kt">int</span> <span class="n">maps</span><span class="p">[</span><span class="mi">1005</span><span class="p">][</span><span class="mi">1005</span><span class="p">],</span><span class="n">v</span><span class="p">[</span><span class="mi">1005</span><span class="p">],</span><span class="n">d</span><span class="p">[</span><span class="mi">1005</span><span class="p">];</span>  <span class="c1">//v 表示是否已经过遍历 d 表示从源到点当前最短路
</span></span></span><span class="line"><span class="cl"><span class="c1"></span><span class="kt">int</span> <span class="n">n</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">void</span> <span class="nf">Dijkstra</span><span class="p">(</span><span class="kt">int</span> <span class="n">s</span><span class="p">,</span><span class="kt">int</span> <span class="n">t</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">i</span><span class="p">,</span><span class="n">j</span><span class="p">,</span><span class="n">k</span><span class="p">,</span><span class="n">mini</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="n">d</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">=</span><span class="n">INF</span><span class="p">;</span>                      <span class="c1">//除源点设为 0 距离外 其他先设为无穷大
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>    <span class="n">d</span><span class="p">[</span><span class="n">s</span><span class="p">]</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>         <span class="c1">//n 点循环 n 次 , 找出 n 个 k, 找 n 个点
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>    <span class="p">{</span>
</span></span><span class="line"><span class="cl">        <span class="n">mini</span><span class="o">=</span><span class="n">INF</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">k</span><span class="o">=-</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">j</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">j</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">j</span><span class="o">++</span><span class="p">)</span>              <span class="c1">//在所有未标记点中 选 d 值最小的点
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="k">if</span><span class="p">(</span><span class="o">!</span><span class="n">v</span><span class="p">[</span><span class="n">j</span><span class="p">]</span> <span class="o">&amp;&amp;</span> <span class="n">d</span><span class="p">[</span><span class="n">j</span><span class="p">]</span><span class="o">&lt;</span><span class="n">mini</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">                <span class="n">mini</span><span class="o">=</span><span class="n">d</span><span class="p">[</span><span class="n">k</span><span class="o">=</span><span class="n">j</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">        <span class="n">v</span><span class="p">[</span><span class="n">k</span><span class="p">]</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span>                         <span class="c1">//标记节点
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>        <span class="k">if</span><span class="p">(</span><span class="n">k</span><span class="o">==</span><span class="n">t</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="p">{</span>
</span></span><span class="line"><span class="cl">            <span class="n">printf</span><span class="p">(</span><span class="s">&#34;%d</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">,</span><span class="n">d</span><span class="p">[</span><span class="n">t</span><span class="p">]);</span>
</span></span><span class="line"><span class="cl">            <span class="k">return</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">j</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">j</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">j</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span><span class="p">(</span><span class="o">!</span><span class="n">v</span><span class="p">[</span><span class="n">j</span><span class="p">]</span> <span class="o">&amp;&amp;</span> <span class="p">(</span><span class="n">d</span><span class="p">[</span><span class="n">k</span><span class="p">]</span><span class="o">+</span><span class="n">maps</span><span class="p">[</span><span class="n">k</span><span class="p">][</span><span class="n">j</span><span class="p">])</span><span class="o">&lt;</span><span class="n">d</span><span class="p">[</span><span class="n">j</span><span class="p">])</span>   <span class="c1">//表示从 k 出发的点，对于所有边，更新相连点
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>                <span class="n">d</span><span class="p">[</span><span class="n">j</span><span class="p">]</span><span class="o">=</span><span class="n">d</span><span class="p">[</span><span class="n">k</span><span class="p">]</span><span class="o">+</span><span class="n">maps</span><span class="p">[</span><span class="n">k</span><span class="p">][</span><span class="n">j</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">()</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">T</span><span class="p">,</span><span class="n">i</span><span class="p">,</span><span class="n">j</span><span class="p">,</span><span class="n">x</span><span class="p">,</span><span class="n">y</span><span class="p">,</span><span class="n">D</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d %d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">T</span><span class="p">,</span><span class="o">&amp;</span><span class="n">n</span><span class="p">)</span><span class="o">!=</span><span class="n">EOF</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">    <span class="p">{</span>
</span></span><span class="line"><span class="cl">        <span class="n">memset</span><span class="p">(</span><span class="n">v</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="k">sizeof</span><span class="p">(</span><span class="n">v</span><span class="p">));</span>            <span class="c1">//清除标记
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>        <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="k">for</span><span class="p">(</span><span class="n">j</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">j</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">j</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">                <span class="n">maps</span><span class="p">[</span><span class="n">i</span><span class="p">][</span><span class="n">j</span><span class="p">]</span><span class="o">=</span><span class="n">INF</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">T</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d%d%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">x</span><span class="p">,</span><span class="o">&amp;</span><span class="n">y</span><span class="p">,</span><span class="o">&amp;</span><span class="n">D</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span><span class="p">(</span><span class="n">maps</span><span class="p">[</span><span class="n">x</span><span class="p">][</span><span class="n">y</span><span class="p">]</span><span class="o">&gt;</span><span class="n">D</span><span class="p">)</span>               <span class="c1">//可能有多条路，只记录最短的
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>                <span class="n">maps</span><span class="p">[</span><span class="n">x</span><span class="p">][</span><span class="n">y</span><span class="p">]</span><span class="o">=</span><span class="n">D</span><span class="p">,</span><span class="n">maps</span><span class="p">[</span><span class="n">y</span><span class="p">][</span><span class="n">x</span><span class="p">]</span><span class="o">=</span><span class="n">D</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="n">Dijkstra</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span><span class="n">n</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>牛客暑假多校第五场</title><link>https://lruihao.cn/posts/nowcodersummer-5th/</link><pubDate>Thu, 02 Aug 2018 21:27:02 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/nowcodersummer-5th/</guid><description><![CDATA[<p><a href="https://pan.baidu.com/s/1VP9Wn0OF4SVaqEVwpNralA"target="_blank" rel="external nofollow noopener noreferrer">题目链接 密码：l9sn<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a><br>
终于不爆零了，但是还是 wa 了无数次，有时候代码感觉都差不多</p>
<h2 id="g-max">G-max</h2>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cm">/*
</span></span></span><span class="line"><span class="cl"><span class="cm">//wa
</span></span></span><span class="line"><span class="cl"><span class="cm">#include&lt;bits/stdc++.h&gt;
</span></span></span><span class="line"><span class="cl"><span class="cm">using namespace std;
</span></span></span><span class="line"><span class="cl"><span class="cm">
</span></span></span><span class="line"><span class="cl"><span class="cm">int main(){
</span></span></span><span class="line"><span class="cl"><span class="cm">    int n,c;//好像不会爆 int 吧，头晕
</span></span></span><span class="line"><span class="cl"><span class="cm">    cin&gt;&gt;c&gt;&gt;n;
</span></span></span><span class="line"><span class="cl"><span class="cm">    int t=n/c;
</span></span></span><span class="line"><span class="cl"><span class="cm">    if(t&lt;1) cout&lt;&lt;&#34;-1\n&#34;;//
</span></span></span><span class="line"><span class="cl"><span class="cm">    else if(t==1) cout&lt;&lt;c*c&lt;&lt;endl;
</span></span></span><span class="line"><span class="cl"><span class="cm">    else cout&lt;&lt;(t*c)*((t-1)*c)&lt;&lt;endl;
</span></span></span><span class="line"><span class="cl"><span class="cm">  return 0;
</span></span></span><span class="line"><span class="cl"><span class="cm">}*/</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="c1">//AC
</span></span></span><span class="line"><span class="cl"><span class="c1"></span><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">long</span> <span class="kt">long</span> <span class="n">n</span><span class="p">,</span><span class="n">c</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">c</span><span class="o">&gt;&gt;</span><span class="n">n</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">long</span> <span class="kt">long</span> <span class="n">t</span><span class="o">=</span><span class="n">n</span><span class="o">/</span><span class="n">c</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">t</span><span class="o">&lt;</span><span class="mi">1</span><span class="p">)</span> <span class="n">cout</span><span class="o">&lt;&lt;-</span><span class="mi">1</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">t</span><span class="o">==</span><span class="mi">1</span><span class="p">)</span> <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">c</span><span class="o">*</span><span class="n">c</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">else</span> <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="p">(</span><span class="n">t</span><span class="o">*</span><span class="n">c</span><span class="p">)</span><span class="o">*</span><span class="p">((</span><span class="n">t</span><span class="o">-</span><span class="mi">1</span><span class="p">)</span><span class="o">*</span><span class="n">c</span><span class="p">)</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">  <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div><h2 id="j-plan">J-plan</h2>
<div class="highlight" id="id-2"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cm">/*枚举所有情况
</span></span></span><span class="line"><span class="cl"><span class="cm">全买双人 n%2  0 or 1//剩 1 个人的时候，可以多开一间房或者退一间 2 人房开一间 3 人房
</span></span></span><span class="line"><span class="cl"><span class="cm">全买 3 人 n%3  0 or 1 or 2
</span></span></span><span class="line"><span class="cl"><span class="cm">再比较大小
</span></span></span><span class="line"><span class="cl"><span class="cm">*/</span>
</span></span><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp">#define INF 1&lt;&lt;20
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="k">typedef</span> <span class="kt">long</span> <span class="kt">long</span> <span class="n">ll</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="n">ll</span> <span class="nf">min</span><span class="p">(</span><span class="n">ll</span> <span class="n">a</span><span class="p">,</span><span class="n">ll</span> <span class="n">b</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">a</span><span class="o">&lt;</span><span class="n">b</span><span class="o">?</span><span class="nl">a</span><span class="p">:</span><span class="n">b</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="n">ll</span> <span class="n">n</span><span class="p">,</span><span class="n">p2</span><span class="p">,</span><span class="n">p3</span><span class="p">,</span><span class="n">sum</span><span class="p">,</span><span class="n">sum1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">n</span><span class="o">&gt;&gt;</span><span class="n">p2</span><span class="o">&gt;&gt;</span><span class="n">p3</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">n</span><span class="o">%</span><span class="mi">2</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="n">sum</span><span class="o">=</span><span class="n">p2</span><span class="o">*</span><span class="p">(</span><span class="n">n</span><span class="o">/</span><span class="mi">2</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span> <span class="n">sum</span><span class="o">=</span><span class="n">p2</span><span class="o">*</span><span class="p">(</span><span class="n">n</span><span class="o">/</span><span class="mi">2</span><span class="p">)</span><span class="o">+</span><span class="n">min</span><span class="p">(</span><span class="n">min</span><span class="p">(</span><span class="n">p2</span><span class="p">,</span><span class="n">p3</span><span class="p">),</span><span class="n">p3</span><span class="o">-</span><span class="n">p2</span><span class="p">);</span><span class="c1">//退二买三；
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">n</span><span class="o">%</span><span class="mi">3</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="n">sum1</span><span class="o">=</span><span class="n">p3</span><span class="o">*</span><span class="p">(</span><span class="n">n</span><span class="o">/</span><span class="mi">3</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">n</span><span class="o">%</span><span class="mi">3</span><span class="o">==</span><span class="mi">1</span><span class="p">)</span> <span class="n">sum1</span><span class="o">=</span><span class="n">p3</span><span class="o">*</span><span class="p">(</span><span class="n">n</span><span class="o">/</span><span class="mi">3</span><span class="p">)</span><span class="o">+</span><span class="n">min</span><span class="p">(</span><span class="n">min</span><span class="p">(</span><span class="n">p2</span><span class="p">,</span><span class="n">p3</span><span class="p">),</span><span class="mi">2</span><span class="o">*</span><span class="n">p2</span><span class="o">-</span><span class="n">p3</span><span class="p">);</span><span class="c1">//退 3 买 2*2
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>        <span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">n</span><span class="o">%</span><span class="mi">3</span><span class="o">==</span><span class="mi">2</span><span class="p">)</span> <span class="n">sum1</span><span class="o">=</span><span class="n">p3</span><span class="o">*</span><span class="p">(</span><span class="n">n</span><span class="o">/</span><span class="mi">3</span><span class="p">)</span><span class="o">+</span><span class="n">min</span><span class="p">(</span><span class="n">p3</span><span class="p">,</span><span class="n">p2</span><span class="p">);</span><span class="c1">//退 3 买 3*2
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>        <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">min</span><span class="p">(</span><span class="n">sum1</span><span class="p">,</span><span class="n">sum</span><span class="p">)</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">  <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>食物链-poj1182（带权并查集经典模板）</title><link>https://lruihao.cn/posts/poj1182/</link><pubDate>Thu, 02 Aug 2018 11:10:37 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/poj1182/</guid><description><![CDATA[<p><a href="http://poj.org/problem?id=1182"target="_blank" rel="external nofollow noopener noreferrer">题目链接<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a><br>
<a href="https://blog.csdn.net/freezhanacmore/article/details/8767413"target="_blank" rel="external nofollow noopener noreferrer">思路参考 1<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a>,<a href="https://blog.csdn.net/niushuai666/article/details/6981689"target="_blank" rel="external nofollow noopener noreferrer">思路参考 2<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a>（没看懂）</p>
<p><del>先占坑，有时间再理理思路。</del></p>
<blockquote>
<p>同一棵树中</p>
<blockquote>
<p>d=1, 即 x 和 y 是同类，则需满足 r[x]==r[y]<br>
d=2,x 应该吃了 y, 也就是 (r[x]+1)%3 == r[y] </p>
</blockquote>
<p>不同树合并且更新关系 (<strong>x 树做主根</strong>)<br>
&rsquo; <strong>如果 x 和 y 为关系 r1, y 和 z 为关系 r2， 那么 x 和 z 的关系就是（r1+r2）%3</strong></p>
<blockquote>
<p>如果 d==1 则 x 和 y 是同类 ，那么 y 对 x 的关系是 0, 如果 d==2 , 则 x 吃了 y, 那么 y 对 x 的关系是 1, x 对 y 的关系是 2。综上所述 , 无论 d 为 1 或者是为 2, y 对 x 的关系都是 d-1。<br>
fy 对 y 的关系为 3-r[y] （有点互补的感觉，注意这里是不同类喔）<br>
y 对 x 的关系为 d-1,<br>
x 对 fx 的关系为 r[x]<br>
所以 fy 对 fx 的关系是（3-r[y] + d-1 + r[x]）%3。可以借助向量图理解 fy-&gt;y-&gt;x-&gt;fx </p>
</blockquote>
</blockquote>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span><span class="lnt">33
</span><span class="lnt">34
</span><span class="lnt">35
</span><span class="lnt">36
</span><span class="lnt">37
</span><span class="lnt">38
</span><span class="lnt">39
</span><span class="lnt">40
</span><span class="lnt">41
</span><span class="lnt">42
</span><span class="lnt">43
</span><span class="lnt">44
</span><span class="lnt">45
</span><span class="lnt">46
</span><span class="lnt">47
</span><span class="lnt">48
</span><span class="lnt">49
</span><span class="lnt">50
</span><span class="lnt">51
</span><span class="lnt">52
</span><span class="lnt">53
</span><span class="lnt">54
</span><span class="lnt">55
</span><span class="lnt">56
</span><span class="lnt">57
</span><span class="lnt">58
</span><span class="lnt">59
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;cstdio&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span>
</span></span><span class="line"><span class="cl"><span class="k">const</span> <span class="kt">int</span> <span class="n">maxn</span> <span class="o">=</span> <span class="mi">50000</span><span class="o">+</span><span class="mi">10</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">p</span><span class="p">[</span><span class="n">maxn</span><span class="p">];</span> <span class="c1">//存父节点
</span></span></span><span class="line"><span class="cl"><span class="c1"></span><span class="kt">int</span> <span class="n">r</span><span class="p">[</span><span class="n">maxn</span><span class="p">];</span><span class="c1">//存与父节点的关系 0 同一类，1 被父节点吃，2 吃父节点
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>
</span></span><span class="line"><span class="cl"><span class="kt">void</span> <span class="nf">set</span><span class="p">(</span><span class="kt">int</span> <span class="n">n</span><span class="p">)</span> <span class="c1">//初始化
</span></span></span><span class="line"><span class="cl"><span class="c1"></span><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">x</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span> <span class="n">x</span> <span class="o">&lt;=</span> <span class="n">n</span><span class="p">;</span> <span class="n">x</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">    <span class="p">{</span>
</span></span><span class="line"><span class="cl">        <span class="n">p</span><span class="p">[</span><span class="n">x</span><span class="p">]</span> <span class="o">=</span> <span class="n">x</span><span class="p">;</span> <span class="c1">//开始自己是自己的父亲节点
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>        <span class="n">r</span><span class="p">[</span><span class="n">x</span><span class="p">]</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span><span class="c1">//开始自己就是自己的父亲，每一个点均独立
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>    <span class="p">}</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">find</span><span class="p">(</span><span class="kt">int</span> <span class="n">x</span><span class="p">)</span> <span class="c1">//找父亲节点
</span></span></span><span class="line"><span class="cl"><span class="c1"></span><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">x</span> <span class="o">==</span> <span class="n">p</span><span class="p">[</span><span class="n">x</span><span class="p">])</span> <span class="k">return</span> <span class="n">x</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">t</span> <span class="o">=</span> <span class="n">p</span><span class="p">[</span><span class="n">x</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="n">p</span><span class="p">[</span><span class="n">x</span><span class="p">]</span> <span class="o">=</span> <span class="nf">find</span><span class="p">(</span><span class="n">p</span><span class="p">[</span><span class="n">x</span><span class="p">]);</span>
</span></span><span class="line"><span class="cl">    <span class="n">r</span><span class="p">[</span><span class="n">x</span><span class="p">]</span> <span class="o">=</span> <span class="p">(</span><span class="n">r</span><span class="p">[</span><span class="n">x</span><span class="p">]</span><span class="o">+</span><span class="n">r</span><span class="p">[</span><span class="n">t</span><span class="p">])</span><span class="o">%</span><span class="mi">3</span><span class="p">;</span> <span class="c1">//回溯由子节点与父节点的关系和父节点与根节点的关系找子节点与根节点的关系
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>    <span class="k">return</span> <span class="n">p</span><span class="p">[</span><span class="n">x</span><span class="p">];</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">void</span> <span class="nf">Union</span><span class="p">(</span><span class="kt">int</span> <span class="n">x</span><span class="p">,</span> <span class="kt">int</span> <span class="n">y</span><span class="p">,</span> <span class="kt">int</span> <span class="n">d</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">fx</span> <span class="o">=</span> <span class="nf">find</span><span class="p">(</span><span class="n">x</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">fy</span> <span class="o">=</span> <span class="nf">find</span><span class="p">(</span><span class="n">y</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="n">p</span><span class="p">[</span><span class="n">fy</span><span class="p">]</span> <span class="o">=</span> <span class="n">fx</span><span class="p">;</span> <span class="c1">//合并树 注意：被 x 吃，所以以 x 的根为父
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>    <span class="n">r</span><span class="p">[</span><span class="n">fy</span><span class="p">]</span> <span class="o">=</span> <span class="p">(</span><span class="n">r</span><span class="p">[</span><span class="n">x</span><span class="p">]</span><span class="o">-</span><span class="n">r</span><span class="p">[</span><span class="n">y</span><span class="p">]</span><span class="o">+</span><span class="mi">3</span><span class="o">+</span><span class="p">(</span><span class="n">d</span><span class="o">-</span><span class="mi">1</span><span class="p">))</span><span class="o">%</span><span class="mi">3</span><span class="p">;</span> <span class="c1">//对应更新与父节点的关系
</span></span></span><span class="line"><span class="cl"><span class="c1"></span><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">()</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">n</span><span class="p">,</span> <span class="n">m</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="nf">scanf</span><span class="p">(</span><span class="s">&#34;%d%d&#34;</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">n</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">m</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="nf">set</span><span class="p">(</span><span class="n">n</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">ans</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">d</span><span class="p">,</span> <span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">m</span><span class="o">--</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">    <span class="p">{</span>
</span></span><span class="line"><span class="cl">        <span class="nf">scanf</span><span class="p">(</span><span class="s">&#34;%d%d%d&#34;</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">d</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">x</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">y</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">x</span> <span class="o">&gt;</span> <span class="n">n</span> <span class="o">||</span> <span class="n">y</span> <span class="o">&gt;</span> <span class="n">n</span> <span class="o">||</span> <span class="p">(</span><span class="n">d</span> <span class="o">==</span> <span class="mi">2</span> <span class="o">&amp;&amp;</span> <span class="n">x</span> <span class="o">==</span> <span class="n">y</span><span class="p">))</span> <span class="n">ans</span><span class="o">++</span><span class="p">;</span> <span class="c1">//如果节点编号大于最大编号，或者自己吃自己，说谎
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="nf">find</span><span class="p">(</span><span class="n">x</span><span class="p">)</span> <span class="o">==</span> <span class="nf">find</span><span class="p">(</span><span class="n">y</span><span class="p">))</span> <span class="c1">//如果原来有关系，也就是在同一棵树中，那么直接判断是否说谎
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>        <span class="p">{</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span><span class="p">(</span><span class="n">d</span> <span class="o">==</span> <span class="mi">1</span> <span class="o">&amp;&amp;</span> <span class="n">r</span><span class="p">[</span><span class="n">x</span><span class="p">]</span> <span class="o">!=</span> <span class="n">r</span><span class="p">[</span><span class="n">y</span><span class="p">])</span> <span class="n">ans</span><span class="o">++</span><span class="p">;</span> <span class="c1">//如果 x 和 y 不属于同一类
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="k">if</span><span class="p">(</span><span class="n">d</span> <span class="o">==</span> <span class="mi">2</span> <span class="o">&amp;&amp;</span> <span class="p">(</span><span class="n">r</span><span class="p">[</span><span class="n">x</span><span class="p">]</span><span class="o">+</span><span class="mi">1</span><span class="p">)</span><span class="o">%</span><span class="mi">3</span> <span class="o">!=</span> <span class="n">r</span><span class="p">[</span><span class="n">y</span><span class="p">])</span> <span class="n">ans</span><span class="o">++</span><span class="p">;</span> <span class="c1">// 如果 x 没有吃 y （注意要对应 Uinon(x, y) 的情况，否则一路 WA 到死啊！！！)
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span> <span class="nf">Union</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="n">d</span><span class="p">);</span> <span class="c1">//如果开始没有关系，则建立关系
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="nf">printf</span><span class="p">(</span><span class="s">&#34;%d</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">,</span> <span class="n">ans</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>小希的迷宫-HDU-1272（并查集 or 树性质）</title><link>https://lruihao.cn/posts/hdu1272/</link><pubDate>Wed, 01 Aug 2018 21:45:50 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/hdu1272/</guid><description><![CDATA[<h2 id="题目链接小希的迷宫httpacmhdueducnshowproblemphppid1272">题目链接：<a href="http://acm.hdu.edu.cn/showproblem.php?pid=1272"target="_blank" rel="external nofollow noopener noreferrer">小希的迷宫<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></h2>
<h2 id="并查集">并查集：</h2>
<ul>
<li>无回路</li>
<li>单连通</li>
</ul>
<p>并查集做，首先想到的是判断两个点是否连通，不连通就合并，已连通的话说明会形成<strong>回路</strong>，则可以判定 No，交了一发错了。<br>
想了一下没有考虑到多个连通域的情况，该题必须只有<strong>一个连通域</strong></p>
<h2 id="树的性质">树的性质：</h2>
<p>既然单连通无回路，则这肯定是一棵树；那么 edge=v-1;</p>
<p>最后注意空树的情况，至于自环我这里 No 也过了，没有去验证自环 Yes 的情况了</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span><span class="lnt">33
</span><span class="lnt">34
</span><span class="lnt">35
</span><span class="lnt">36
</span><span class="lnt">37
</span><span class="lnt">38
</span><span class="lnt">39
</span><span class="lnt">40
</span><span class="lnt">41
</span><span class="lnt">42
</span><span class="lnt">43
</span><span class="lnt">44
</span><span class="lnt">45
</span><span class="lnt">46
</span><span class="lnt">47
</span><span class="lnt">48
</span><span class="lnt">49
</span><span class="lnt">50
</span><span class="lnt">51
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="c1">//并查集
</span></span></span><span class="line"><span class="cl"><span class="c1"></span><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">pre</span><span class="p">[</span><span class="mi">100001</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">find</span><span class="p">(</span><span class="kt">int</span> <span class="n">root</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">son</span><span class="p">,</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">son</span><span class="o">=</span><span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">root</span><span class="o">!=</span><span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">        <span class="n">root</span><span class="o">=</span><span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">son</span><span class="o">!=</span><span class="n">root</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">t</span><span class="o">=</span><span class="n">pre</span><span class="p">[</span><span class="n">son</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="n">pre</span><span class="p">[</span><span class="n">son</span><span class="p">]</span><span class="o">=</span><span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">son</span><span class="o">=</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">void</span> <span class="nf">join</span><span class="p">(</span><span class="kt">int</span> <span class="n">a</span><span class="p">,</span><span class="kt">int</span> <span class="n">b</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">x</span><span class="o">=</span><span class="n">find</span><span class="p">(</span><span class="n">a</span><span class="p">),</span><span class="n">y</span><span class="o">=</span><span class="n">find</span><span class="p">(</span><span class="n">b</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">x</span><span class="o">!=</span><span class="n">y</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="n">pre</span><span class="p">[</span><span class="n">y</span><span class="p">]</span><span class="o">=</span><span class="n">x</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">,</span><span class="n">flag</span><span class="p">,</span><span class="n">i</span><span class="p">,</span><span class="n">sum</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="k">while</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">	<span class="p">{</span>
</span></span><span class="line"><span class="cl">		<span class="n">flag</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">		<span class="k">while</span><span class="p">(</span><span class="o">~</span><span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">a</span><span class="p">,</span><span class="o">&amp;</span><span class="n">b</span><span class="p">)</span> <span class="o">&amp;&amp;</span> <span class="n">a</span><span class="o">!=</span><span class="mi">0</span> <span class="o">&amp;&amp;</span> <span class="n">b</span><span class="o">!=</span><span class="mi">0</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span><span class="p">(</span><span class="n">a</span><span class="o">==-</span><span class="mi">1</span> <span class="o">&amp;&amp;</span> <span class="n">b</span><span class="o">==-</span><span class="mi">1</span><span class="p">)</span> <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span><span class="p">(</span><span class="n">pre</span><span class="p">[</span><span class="n">a</span><span class="p">]</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span><span class="n">pre</span><span class="p">[</span><span class="n">a</span><span class="p">]</span><span class="o">=</span><span class="n">a</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span><span class="p">(</span><span class="n">pre</span><span class="p">[</span><span class="n">b</span><span class="p">]</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span><span class="n">pre</span><span class="p">[</span><span class="n">b</span><span class="p">]</span><span class="o">=</span><span class="n">b</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span><span class="p">(</span><span class="n">find</span><span class="p">(</span><span class="n">a</span><span class="p">)</span><span class="o">==</span><span class="n">find</span><span class="p">(</span><span class="n">b</span><span class="p">))</span><span class="n">flag</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">			<span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">flag</span><span class="o">!=</span><span class="mi">1</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">			<span class="n">join</span><span class="p">(</span><span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">		<span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">sum</span> <span class="o">=</span> <span class="mi">0</span><span class="p">,</span><span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="mi">100001</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span><span class="p">(</span><span class="n">pre</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">==</span><span class="n">i</span><span class="p">)</span><span class="n">sum</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="n">pre</span><span class="p">[</span><span class="n">i</span><span class="p">]</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">sum</span><span class="o">&gt;</span><span class="mi">1</span> <span class="o">||</span> <span class="n">flag</span> <span class="o">==</span> <span class="mi">1</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">			<span class="n">printf</span><span class="p">(</span><span class="s">&#34;No</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span>
</span></span><span class="line"><span class="cl">			<span class="n">printf</span><span class="p">(</span><span class="s">&#34;Yes</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">	<span class="p">}</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl"><span class="c1">//1 2 3 4 0 0 No 没有连通
</span></span></span><span class="line"><span class="cl"><span class="c1">//0 0 Yes
</span></span></span><span class="line"><span class="cl"><span class="c1">//1 1 0 0 No（该代码）
</span></span></span></code></pre></td></tr></table>
</div>
</div><div class="highlight" id="id-2"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-C" data-lang="C"><span class="line"><span class="cl"><span class="c1">//树性质
</span></span></span><span class="line"><span class="cl"><span class="c1"></span><span class="cp">#include</span> <span class="cpf">&lt;stdio.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="kt">bool</span> <span class="n">s</span><span class="p">[</span><span class="mi">100001</span><span class="p">];</span>
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">()</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>	<span class="kt">int</span> <span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">,</span><span class="n">i</span><span class="p">,</span><span class="n">len</span><span class="p">,</span><span class="n">num</span><span class="p">,</span><span class="n">v</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="mi">100001</span><span class="p">;</span><span class="o">++</span><span class="n">i</span><span class="p">)</span>	<span class="n">s</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">=</span><span class="nb">false</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="n">len</span><span class="o">=</span><span class="mi">0</span><span class="p">,</span><span class="n">num</span><span class="o">=</span><span class="mi">0</span><span class="p">,</span><span class="n">v</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="k">while</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">	<span class="p">{</span>	<span class="nf">scanf</span><span class="p">(</span><span class="s">&#34;%d%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">a</span><span class="p">,</span><span class="o">&amp;</span><span class="n">b</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span><span class="p">(</span><span class="n">a</span><span class="o">==-</span><span class="mi">1</span><span class="o">&amp;&amp;</span><span class="n">b</span><span class="o">==-</span><span class="mi">1</span><span class="p">)</span>	<span class="k">break</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span><span class="p">(</span><span class="n">a</span><span class="o">==</span><span class="mi">0</span><span class="o">&amp;&amp;</span><span class="n">b</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">		<span class="p">{</span>	<span class="k">if</span><span class="p">(</span><span class="n">v</span><span class="o">==</span><span class="mi">0</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">			<span class="p">{</span>	<span class="nf">printf</span><span class="p">(</span><span class="s">&#34;Yes</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">				<span class="k">continue</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">			<span class="p">}</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span><span class="p">(</span><span class="n">num</span><span class="o">==</span><span class="n">len</span><span class="o">-</span><span class="mi">1</span><span class="p">)</span>	<span class="c1">//划重点！！
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>				<span class="nf">printf</span><span class="p">(</span><span class="s">&#34;Yes</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">			<span class="k">else</span> <span class="nf">printf</span><span class="p">(</span><span class="s">&#34;No</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">			<span class="n">num</span><span class="o">=</span><span class="n">len</span><span class="o">=</span><span class="n">v</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">			<span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="mi">100001</span><span class="p">;</span><span class="o">++</span><span class="n">i</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">				<span class="n">s</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">=</span><span class="nb">false</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">			<span class="k">continue</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">		<span class="p">}</span>
</span></span><span class="line"><span class="cl">		<span class="n">v</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span><span class="p">(</span><span class="n">s</span><span class="p">[</span><span class="n">a</span><span class="p">]</span><span class="o">==</span><span class="nb">false</span><span class="p">)</span>		<span class="n">len</span><span class="o">++</span><span class="p">;</span><span class="c1">//点数
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="k">if</span><span class="p">(</span><span class="n">s</span><span class="p">[</span><span class="n">b</span><span class="p">]</span><span class="o">==</span><span class="nb">false</span><span class="p">)</span>		<span class="n">len</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">		<span class="n">s</span><span class="p">[</span><span class="n">a</span><span class="p">]</span><span class="o">=</span><span class="n">s</span><span class="p">[</span><span class="n">b</span><span class="p">]</span><span class="o">=</span><span class="nb">true</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">		<span class="n">num</span><span class="o">++</span><span class="p">;</span><span class="c1">//边数
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>	<span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>How Many Answers Are Wrong-hdu3038（带权并查集）</title><link>https://lruihao.cn/posts/hdu3038/</link><pubDate>Wed, 01 Aug 2018 11:45:53 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/hdu3038/</guid><description><![CDATA[<p>题目链接：<a href="http://acm.hdu.edu.cn/showproblem.php?pid=3038"target="_blank" rel="external nofollow noopener noreferrer">How Many Answers Are Wrong<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a><br>
思路参考：<a href="https://blog.csdn.net/duan_1998/article/details/70196576"target="_blank" rel="external nofollow noopener noreferrer">本题直接参考<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a>,<a href="https://blog.csdn.net/dextrad_ihacker/article/details/51016017"target="_blank" rel="external nofollow noopener noreferrer">图文解释<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span><span class="lnt">33
</span><span class="lnt">34
</span><span class="lnt">35
</span><span class="lnt">36
</span><span class="lnt">37
</span><span class="lnt">38
</span><span class="lnt">39
</span><span class="lnt">40
</span><span class="lnt">41
</span><span class="lnt">42
</span><span class="lnt">43
</span><span class="lnt">44
</span><span class="lnt">45
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="k">typedef</span> <span class="kt">long</span> <span class="kt">long</span> <span class="n">LL</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">pre</span><span class="p">[</span><span class="mi">200010</span><span class="p">],</span><span class="n">ranks</span><span class="p">[</span><span class="mi">200010</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">find</span><span class="p">(</span><span class="kt">int</span> <span class="n">root</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">]</span> <span class="o">!=</span> <span class="n">root</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">    <span class="p">{</span>
</span></span><span class="line"><span class="cl">        <span class="kt">int</span> <span class="n">f</span> <span class="o">=</span> <span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">]</span> <span class="o">=</span> <span class="n">find</span><span class="p">(</span><span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">]);</span><span class="c1">//递归路径压缩
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>        <span class="n">ranks</span><span class="p">[</span><span class="n">root</span><span class="p">]</span> <span class="o">+=</span> <span class="n">ranks</span><span class="p">[</span><span class="n">f</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="cm">/*精髓假如一开始没关系，那么用 rank 数组来表示 a，b 各自到各自祖先的距离。
</span></span></span><span class="line"><span class="cl"><span class="cm">        那么在把 a 的祖先给 b 的祖先当父亲之后，那么 b 到祖先的距离也就是 rank[b] 就要再加上 b 原本的祖先到 a 的祖先的距离，更新一下，
</span></span></span><span class="line"><span class="cl"><span class="cm">        其中 find 函数（找根节点的函数）里 rank[x]+=rank[pre[x]]（这里 pre 数组存的是对应数的父节点）*/</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">];</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">n</span><span class="p">,</span><span class="n">m</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="o">~</span><span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">n</span><span class="p">,</span><span class="o">&amp;</span><span class="n">m</span><span class="p">)){</span>
</span></span><span class="line"><span class="cl">        <span class="kt">int</span> <span class="n">ans</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span> <span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span> <span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="n">pre</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">=</span><span class="n">i</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">memset</span><span class="p">(</span><span class="n">ranks</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="k">sizeof</span><span class="p">(</span><span class="n">ranks</span><span class="p">));</span>
</span></span><span class="line"><span class="cl">        <span class="k">while</span><span class="p">(</span><span class="n">m</span><span class="o">--</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="kt">int</span> <span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">,</span><span class="n">c</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d%d%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">a</span><span class="p">,</span><span class="o">&amp;</span><span class="n">b</span><span class="p">,</span><span class="o">&amp;</span><span class="n">c</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">            <span class="n">a</span><span class="o">--</span><span class="p">;</span><span class="c1">//[a,b]~~(a--,b]
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="kt">int</span> <span class="n">fa</span><span class="o">=</span><span class="n">find</span><span class="p">(</span><span class="n">a</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">            <span class="kt">int</span> <span class="n">fb</span><span class="o">=</span><span class="n">find</span><span class="p">(</span><span class="n">b</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span><span class="p">(</span><span class="n">fa</span><span class="o">!=</span><span class="n">fb</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">                <span class="n">pre</span><span class="p">[</span><span class="n">fb</span><span class="p">]</span><span class="o">=</span><span class="n">fa</span><span class="p">;</span><span class="c1">//注意合并顺序，反过来下面的也要改
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>                <span class="n">ranks</span><span class="p">[</span><span class="n">fb</span><span class="p">]</span><span class="o">=</span><span class="n">ranks</span><span class="p">[</span><span class="n">a</span><span class="p">]</span><span class="o">-</span><span class="n">ranks</span><span class="p">[</span><span class="n">b</span><span class="p">]</span><span class="o">+</span><span class="n">c</span><span class="p">;</span><span class="c1">//更新距离
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="p">}</span>
</span></span><span class="line"><span class="cl">            <span class="k">else</span> <span class="p">{</span>
</span></span><span class="line"><span class="cl">                <span class="k">if</span><span class="p">(</span><span class="n">ranks</span><span class="p">[</span><span class="n">b</span><span class="p">]</span><span class="o">-</span><span class="n">ranks</span><span class="p">[</span><span class="n">a</span><span class="p">]</span><span class="o">!=</span><span class="n">c</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">                    <span class="n">ans</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;%d</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">,</span><span class="n">ans</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>Bear and Finding Criminals-Codeforces680B</title><link>https://lruihao.cn/posts/codeforces680b/</link><pubDate>Tue, 31 Jul 2018 19:32:21 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/codeforces680b/</guid><description><![CDATA[<p>题目链接：<a href="https://codeforces.com/problemset/problem/680/B"target="_blank" rel="external nofollow noopener noreferrer">Bear and Finding Criminals<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></p>
<p>大致题意就是小熊警察住在某个城市，他要抓各个城市的罪犯，现在用一个 BCD 可以知道那个城市里<strong>一定</strong>有罪犯。</p>
<p>一定能确定该城市有小偷的几种情况：</p>
<ol>
<li>
<p>警察所住城市有罪犯，则一定能检测到</p>
</li>
<li>
<p>警察所住城市的左边和右边位置若<strong>都</strong>不为 0，则说明两座城市都有罪犯（只有一边为 1 是不能确定到底哪个城市有罪犯的）</p>
</li>
<li>
<p>警察所在城市的一边检测到有罪犯，但在另一边已经没有城市了，则说明该城市一定有罪犯</p>
</li>
</ol>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">t</span><span class="p">[</span><span class="mi">107</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">()</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">	<span class="kt">int</span> <span class="n">n</span><span class="p">,</span> <span class="n">a</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="k">while</span><span class="p">(</span><span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">n</span><span class="o">&gt;&gt;</span><span class="n">a</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">		<span class="kt">int</span> <span class="n">sum</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">		<span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span> <span class="o">=</span><span class="mi">1</span><span class="p">;</span> <span class="n">i</span> <span class="o">&lt;=</span> <span class="n">n</span><span class="p">;</span> <span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">			<span class="n">cin</span> <span class="o">&gt;&gt;</span> <span class="n">t</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span><span class="p">(</span><span class="n">t</span><span class="p">[</span><span class="n">a</span><span class="p">])</span> <span class="n">sum</span><span class="o">++</span><span class="p">;</span><span class="c1">//小熊所在城市有罪犯
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span> <span class="n">i</span> <span class="o">&lt;=</span> <span class="n">n</span><span class="p">;</span> <span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span><span class="p">(</span><span class="n">a</span><span class="o">-</span><span class="n">i</span> <span class="o">&gt;</span> <span class="mi">0</span><span class="o">&amp;&amp;</span><span class="n">a</span><span class="o">+</span><span class="n">i</span> <span class="o">&lt;=</span> <span class="n">n</span><span class="p">)</span> <span class="p">{</span>
</span></span><span class="line"><span class="cl">				<span class="k">if</span><span class="p">(</span><span class="n">t</span><span class="p">[</span><span class="n">a</span><span class="o">-</span><span class="n">i</span><span class="p">]</span> <span class="o">==</span> <span class="mi">1</span><span class="o">&amp;&amp;</span><span class="n">t</span><span class="p">[</span><span class="n">a</span><span class="o">+</span><span class="n">i</span><span class="p">]</span> <span class="o">==</span> <span class="mi">1</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">					<span class="n">sum</span><span class="o">+=</span><span class="mi">2</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">			<span class="p">}</span>
</span></span><span class="line"><span class="cl">			<span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">a</span><span class="o">-</span><span class="n">i</span> <span class="o">&lt;=</span> <span class="mi">0</span><span class="o">&amp;&amp;</span><span class="n">a</span><span class="o">+</span><span class="n">i</span> <span class="o">&lt;=</span> <span class="n">n</span><span class="p">){</span><span class="c1">//警察在第一个点
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>				<span class="k">if</span><span class="p">(</span><span class="n">t</span><span class="p">[</span><span class="n">a</span><span class="o">+</span><span class="n">i</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">					<span class="n">sum</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">			<span class="p">}</span>
</span></span><span class="line"><span class="cl">			<span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">a</span><span class="o">-</span><span class="n">i</span> <span class="o">&gt;</span> <span class="mi">0</span><span class="o">&amp;&amp;</span><span class="n">a</span><span class="o">+</span><span class="n">i</span> <span class="o">&gt;</span> <span class="n">n</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">				<span class="k">if</span><span class="p">(</span><span class="n">t</span><span class="p">[</span><span class="n">a</span><span class="o">-</span><span class="n">i</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">					<span class="n">sum</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">			<span class="p">}</span>
</span></span><span class="line"><span class="cl">		<span class="p">}</span>
</span></span><span class="line"><span class="cl">		<span class="n">cout</span> <span class="o">&lt;&lt;</span><span class="n">sum</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>Bear and Five Cards-Codeforces680A</title><link>https://lruihao.cn/posts/codeforces680a/</link><pubDate>Tue, 31 Jul 2018 19:22:36 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/codeforces680a/</guid><description><![CDATA[<p>题目链接：<a href="https://codeforces.com/problemset/problem/680/A"target="_blank" rel="external nofollow noopener noreferrer">Bear and Five Cards<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></p>
<p>大致题意就是小熊有 5 张卡片，每张卡片有对应的分数，他可以选择丢弃 2 张相同的或者 3 张相同的卡片，没有相同的就无法丢弃，问小熊剩下的分数最少是多少。</p>
<p>没有想得那么复杂，由于分数最大才 100，所以直接暴力就好了。</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">a</span><span class="p">[</span><span class="mi">5</span><span class="p">],</span><span class="n">b</span><span class="p">[</span><span class="mi">107</span><span class="p">],</span><span class="n">i</span><span class="p">,</span><span class="n">j</span><span class="p">,</span><span class="n">sum</span><span class="o">=</span><span class="mi">0</span><span class="p">,</span><span class="n">sum1</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="mi">5</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">a</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="n">sum</span><span class="o">+=</span><span class="n">a</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="n">sort</span><span class="p">(</span><span class="n">a</span><span class="p">,</span><span class="n">a</span><span class="o">+</span><span class="mi">5</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="n">memset</span><span class="p">(</span><span class="n">b</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="k">sizeof</span><span class="p">(</span><span class="n">b</span><span class="p">));</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="mi">5</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="n">b</span><span class="p">[</span><span class="n">a</span><span class="p">[</span><span class="n">i</span><span class="p">]]</span><span class="o">++</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="mi">107</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">b</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">==</span><span class="mi">2</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="n">sum1</span><span class="o">=</span><span class="n">max</span><span class="p">(</span><span class="mi">2</span><span class="o">*</span><span class="n">i</span><span class="p">,</span><span class="n">sum1</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">b</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">&gt;=</span><span class="mi">3</span><span class="p">)</span> <span class="p">{</span><span class="n">sum1</span><span class="o">=</span><span class="n">max</span><span class="p">(</span><span class="mi">3</span><span class="o">*</span><span class="n">i</span><span class="p">,</span><span class="n">sum1</span><span class="p">);</span><span class="cm">/*cout&lt;&lt;3*i&lt;&lt;&#34; &#34;&lt;&lt;sum1&lt;&lt;endl;*/</span><span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">sum</span><span class="o">-</span><span class="n">sum1</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>how many tables-HDU-1213（并查集求连通域数目）</title><link>https://lruihao.cn/posts/how-tables/</link><pubDate>Tue, 31 Jul 2018 11:12:10 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/how-tables/</guid><description><![CDATA[<p>并查集求连通域数目，初始化 sum=n；
题目链接： <a href="http://acm.hdu.edu.cn/showproblem.php?pid=1213"target="_blank" rel="external nofollow noopener noreferrer">how many tables<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span><span class="lnt">33
</span><span class="lnt">34
</span><span class="lnt">35
</span><span class="lnt">36
</span><span class="lnt">37
</span><span class="lnt">38
</span><span class="lnt">39
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">pre</span><span class="p">[</span><span class="mi">1005</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">find</span><span class="p">(</span><span class="kt">int</span> <span class="n">root</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">son</span><span class="p">,</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">son</span><span class="o">=</span><span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">root</span><span class="o">!=</span><span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">        <span class="n">root</span><span class="o">=</span><span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">son</span><span class="o">!=</span><span class="n">root</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">t</span><span class="o">=</span><span class="n">pre</span><span class="p">[</span><span class="n">son</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="n">pre</span><span class="p">[</span><span class="n">son</span><span class="p">]</span><span class="o">=</span><span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">son</span><span class="o">=</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">n</span><span class="p">,</span><span class="n">m</span><span class="p">,</span><span class="n">t</span><span class="p">,</span><span class="n">sum</span><span class="p">,</span><span class="n">root1</span><span class="p">,</span><span class="n">root2</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">t</span><span class="o">--</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">n</span><span class="o">&gt;&gt;</span><span class="n">m</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">sum</span><span class="o">=</span><span class="n">n</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="n">pre</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">=</span><span class="n">i</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">m</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">root1</span><span class="o">&gt;&gt;</span><span class="n">root2</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="kt">int</span> <span class="n">xx</span><span class="o">=</span><span class="n">find</span><span class="p">(</span><span class="n">root1</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">            <span class="kt">int</span> <span class="n">yy</span><span class="o">=</span><span class="n">find</span><span class="p">(</span><span class="n">root2</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span><span class="p">(</span><span class="n">xx</span><span class="o">!=</span><span class="n">yy</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">                <span class="n">pre</span><span class="p">[</span><span class="n">xx</span><span class="p">]</span><span class="o">=</span><span class="n">yy</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">                <span class="n">sum</span><span class="o">--</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">sum</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>The-suspects-POJ-1611（并查集）</title><link>https://lruihao.cn/posts/poj-1611/</link><pubDate>Tue, 31 Jul 2018 11:11:31 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/poj-1611/</guid><description><![CDATA[<h2 id="题目链接the-suspectshttppojorgproblemid1611">题目链接：<a href="http://poj.org/problem?id=1611"target="_blank" rel="external nofollow noopener noreferrer">The-suspects<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></h2>
<h2 id="翻译">翻译：</h2>
<p>警察抓贩毒集团。有不同类型的犯罪集团，人员可能重复，集团内的人会相互接触。现在警察在其中一人（0 号）身上搜出毒品，认为与这个人直接接触或通过其他人有间接接触的人都是嫌疑犯。问包括 0 号犯人共有多少嫌疑犯？</p>
<h3 id="input">Input</h3>
<p>多样例输入。<br>
每个测试用例以两个整数 n 和 m 开头，其中 n 为人数，m 为犯罪集团数。你可以假定 0 &lt; n &lt;= 30000 和 0 &lt;= m &lt;= 500。在所有的情况下，每个人都有自己独特的整数编号 0 到 n−1, 且 0 号是公认的嫌疑犯。<br>
接下来 m 行输入，每个犯罪集团一行。每一行从一个整数 k 开始，它本身表示集团内成员的数量。按照成员的数量，在这个组中有 k 个整数表示人员。一行中的所有整数都被至少一个空格隔开。<br>
n = 0 且 m = 0 时输入结束。</p>
<h3 id="output">Output</h3>
<p>对于每个样例，输出嫌疑犯人数。</p>
<h3 id="sample-input">Sample Input</h3>
<pre><code>100 4
2 1 2
5 10 13 11 12 14
2 0 1
2 99 2
200 2
1 5
5 1 2 3 4 5
1 0
0 0
</code></pre>
<h3 id="sample-output">Sample Output</h3>
<pre><code>4
1
</code></pre>
<p>这题也很好理解，AC 代码如下：</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span><span class="lnt">33
</span><span class="lnt">34
</span><span class="lnt">35
</span><span class="lnt">36
</span><span class="lnt">37
</span><span class="lnt">38
</span><span class="lnt">39
</span><span class="lnt">40
</span><span class="lnt">41
</span><span class="lnt">42
</span><span class="lnt">43
</span><span class="lnt">44
</span><span class="lnt">45
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;cstdio&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span>
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">pre</span><span class="p">[</span><span class="mi">30010</span><span class="p">],</span><span class="n">x</span><span class="p">[</span><span class="mi">30010</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">find</span><span class="p">(</span><span class="kt">int</span> <span class="n">root</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">son</span><span class="p">,</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">son</span><span class="o">=</span><span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">root</span><span class="o">!=</span><span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">        <span class="n">root</span><span class="o">=</span><span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">son</span><span class="o">!=</span><span class="n">root</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">t</span><span class="o">=</span><span class="n">pre</span><span class="p">[</span><span class="n">son</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="n">pre</span><span class="p">[</span><span class="n">son</span><span class="p">]</span><span class="o">=</span><span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">son</span><span class="o">=</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">void</span> <span class="nf">join</span><span class="p">(</span><span class="kt">int</span> <span class="n">x</span><span class="p">,</span><span class="kt">int</span> <span class="n">y</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">fx</span><span class="o">=</span><span class="n">find</span><span class="p">(</span><span class="n">x</span><span class="p">),</span><span class="n">fy</span><span class="o">=</span><span class="n">find</span><span class="p">(</span><span class="n">y</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">fx</span><span class="o">!=</span><span class="n">fy</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="n">pre</span><span class="p">[</span><span class="n">fy</span><span class="p">]</span><span class="o">=</span><span class="n">fx</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">n</span><span class="p">,</span><span class="n">m</span><span class="p">,</span><span class="n">i</span><span class="p">,</span><span class="n">k</span><span class="p">,</span><span class="n">sum</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">n</span><span class="p">,</span><span class="o">&amp;</span><span class="n">m</span><span class="p">),</span><span class="n">n</span><span class="o">||</span><span class="n">m</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">sum</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="n">pre</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">=</span><span class="n">i</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">while</span><span class="p">(</span><span class="n">m</span><span class="o">--</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">k</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">            <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">k</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">                <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">x</span><span class="p">[</span><span class="n">i</span><span class="p">]);</span>
</span></span><span class="line"><span class="cl">            <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">k</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">                <span class="n">join</span><span class="p">(</span><span class="n">x</span><span class="p">[</span><span class="n">i</span><span class="o">-</span><span class="mi">1</span><span class="p">],</span><span class="n">x</span><span class="p">[</span><span class="n">i</span><span class="p">]);</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span><span class="p">(</span><span class="n">find</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span><span class="o">==</span><span class="n">find</span><span class="p">(</span><span class="n">i</span><span class="p">))</span> <span class="n">sum</span><span class="o">++</span><span class="p">;</span><span class="c1">//再次查找并压缩路径，注不用 pre[i]
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;%d</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">,</span><span class="n">sum</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>wireless network-POJ-2236（并查集）</title><link>https://lruihao.cn/posts/poj-2236/</link><pubDate>Tue, 31 Jul 2018 11:10:54 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/poj-2236/</guid><description><![CDATA[<h2 id="题目链接wireless-networkhttppojorgproblemid2236">题目链接：<a href="http://poj.org/problem?id=2236"target="_blank" rel="external nofollow noopener noreferrer">wireless network<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></h2>
<h2 id="翻译">翻译：</h2>
<p>南亚发生了一次地震。ACM (Asia Cooperated Medical 亚洲联合医疗队） 已经为膝上型电脑搭建了一个无线网络，但受到了一次不可预知的余震攻击，因此网络中的所有电脑都被破坏了。电脑被逐台修复，网络逐步恢复了工作。由于受到硬件的约束，每台电脑只能与距离它不超过 d 米的其它电脑直接通信。但每台电脑可被看作其它两台电脑的通信中转点，也就是说，如果电脑 A 和电脑 B 可以直接通信，或存在一台电脑 C 既可与 A 也可与 B 通信，那么电脑 A 和电脑 B 之间就能够通信。</p>
<p>在处理网络修复的过程中，工作人员们在任何一个时刻，可以执行两种操作：维修一台电脑，或测试两台电脑是否能够通信。请您找出全部的测试操作。</p>
<h3 id="输入">输入</h3>
<p>第一行包含了两个整数 N 和 d (1 &lt;= N &lt;= 1001, 0 &lt;= d &lt;= 20000)。此处 N 是电脑的数目，编号从 1 到 N；同时，D 是两台电脑之间能够直接通信的最大距离。接下来的 N 行，每行包含两个整数 xi, yi (0 &lt;= xi, yi &lt;= 10000)，表示 N 台电脑的坐标。从第 (N+1) 行到输入结束，是逐一执行的操作，每行包含一个操作，格式是以下两者之一：</p>
<ol>
<li>&ldquo;O p&rdquo; (1 &lt;= p &lt;= N)，表示维护电脑 p 。</li>
<li>&ldquo;S p q&rdquo; (1 &lt;= p, q &lt;= N)，表示测试电脑 p 和 q 是否能够通信。</li>
</ol>
<p>输入不超过 300000 行。</p>
<h3 id="输出">输出</h3>
<p>对于每个测试操作，如果两台电脑能够通信，则打印 &ldquo;SUCCESS&rdquo;；否则，打印 &ldquo;FAIL&rdquo;。</p>
<h3 id="示例输入">示例输入</h3>
<pre><code>4 1
0 1
0 2
0 3
0 4
O 1
O 2
O 4
S 1 4
O 3
S 1 4
</code></pre>
<h3 id="示例输出">示例输出</h3>
<pre><code>FAIL
SUCCESS
</code></pre>
<h3 id="ac-代码">AC 代码：</h3>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span><span class="lnt">33
</span><span class="lnt">34
</span><span class="lnt">35
</span><span class="lnt">36
</span><span class="lnt">37
</span><span class="lnt">38
</span><span class="lnt">39
</span><span class="lnt">40
</span><span class="lnt">41
</span><span class="lnt">42
</span><span class="lnt">43
</span><span class="lnt">44
</span><span class="lnt">45
</span><span class="lnt">46
</span><span class="lnt">47
</span><span class="lnt">48
</span><span class="lnt">49
</span><span class="lnt">50
</span><span class="lnt">51
</span><span class="lnt">52
</span><span class="lnt">53
</span><span class="lnt">54
</span><span class="lnt">55
</span><span class="lnt">56
</span><span class="lnt">57
</span><span class="lnt">58
</span><span class="lnt">59
</span><span class="lnt">60
</span><span class="lnt">61
</span><span class="lnt">62
</span><span class="lnt">63
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cp">#include</span> <span class="cpf">&#34;iostream&#34;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp">#include</span> <span class="cpf">&#34;cstring&#34;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">pre</span><span class="p">[</span><span class="mi">1005</span><span class="p">];</span>
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">x</span><span class="p">[</span><span class="mi">1005</span><span class="p">],</span><span class="n">y</span><span class="p">[</span><span class="mi">1005</span><span class="p">],</span><span class="n">use</span><span class="p">[</span><span class="mi">1005</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">findd</span><span class="p">(</span><span class="kt">int</span> <span class="n">root</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">son</span><span class="p">,</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">son</span><span class="o">=</span><span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">root</span><span class="o">!=</span><span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">        <span class="n">root</span><span class="o">=</span><span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">son</span><span class="o">!=</span><span class="n">root</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">t</span><span class="o">=</span><span class="n">pre</span><span class="p">[</span><span class="n">son</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="n">pre</span><span class="p">[</span><span class="n">son</span><span class="p">]</span><span class="o">=</span><span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">son</span><span class="o">=</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">void</span> <span class="nf">join</span><span class="p">(</span><span class="kt">int</span> <span class="n">x</span><span class="p">,</span><span class="kt">int</span> <span class="n">y</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">fx</span><span class="o">=</span><span class="n">findd</span><span class="p">(</span><span class="n">x</span><span class="p">),</span><span class="n">fy</span><span class="o">=</span><span class="n">findd</span><span class="p">(</span><span class="n">y</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">fx</span><span class="o">!=</span><span class="n">fy</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="n">pre</span><span class="p">[</span><span class="n">fx</span><span class="p">]</span><span class="o">=</span><span class="n">fy</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">dis</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="p">,</span><span class="kt">int</span> <span class="n">num</span><span class="p">,</span><span class="kt">int</span> <span class="n">d</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">    <span class="n">d</span><span class="o">=</span><span class="n">d</span><span class="o">*</span><span class="n">d</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">xx</span><span class="o">=</span><span class="n">x</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">-</span><span class="n">x</span><span class="p">[</span><span class="n">num</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">yy</span><span class="o">=</span><span class="n">y</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">-</span><span class="n">y</span><span class="p">[</span><span class="n">num</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">((</span><span class="n">xx</span><span class="o">*</span><span class="n">xx</span><span class="o">+</span><span class="n">yy</span><span class="o">*</span><span class="n">yy</span><span class="p">)</span><span class="o">&lt;=</span><span class="n">d</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="k">return</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">n</span><span class="p">,</span><span class="n">d</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">char</span> <span class="n">s</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">memset</span><span class="p">(</span><span class="n">use</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="k">sizeof</span><span class="p">(</span><span class="n">use</span><span class="p">));</span>
</span></span><span class="line"><span class="cl">    <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">n</span><span class="o">&gt;&gt;</span><span class="n">d</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="n">pre</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">=</span><span class="n">i</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">x</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">&gt;&gt;</span><span class="n">y</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">s</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">s</span><span class="o">==</span><span class="sc">&#39;O&#39;</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="kt">int</span> <span class="n">num</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">num</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="n">use</span><span class="p">[</span><span class="n">num</span><span class="p">]</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="n">findd</span><span class="p">(</span><span class="n">num</span><span class="p">);</span><span class="c1">//路径压缩
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>            <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">                <span class="k">if</span><span class="p">(</span><span class="n">i</span><span class="o">!=</span><span class="n">num</span><span class="o">&amp;&amp;</span><span class="n">use</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">==</span><span class="mi">1</span><span class="o">&amp;&amp;</span><span class="n">dis</span><span class="p">(</span><span class="n">i</span><span class="p">,</span><span class="n">num</span><span class="p">,</span><span class="n">d</span><span class="p">))</span><span class="c1">//修好了，且可以被合并（自己除外）
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>                    <span class="n">join</span><span class="p">(</span><span class="n">i</span><span class="p">,</span><span class="n">num</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">s</span><span class="o">==</span><span class="sc">&#39;S&#39;</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="kt">int</span> <span class="n">q</span><span class="p">,</span><span class="n">p</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">q</span><span class="o">&gt;&gt;</span><span class="n">p</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span><span class="p">(</span><span class="n">findd</span><span class="p">(</span><span class="n">q</span><span class="p">)</span><span class="o">==</span><span class="n">findd</span><span class="p">(</span><span class="n">p</span><span class="p">))</span>
</span></span><span class="line"><span class="cl">                <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="s">&#34;SUCCESS&#34;</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="k">else</span> <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="s">&#34;FAIL&#34;</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>Piles-with-stones</title><link>https://lruihao.cn/posts/piles-with-stones/</link><pubDate>Tue, 31 Jul 2018 11:09:31 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/piles-with-stones/</guid><description><![CDATA[<p>Codeforces Round #500 (Div. 2)<br>
题目链接：<a href="https://codeforces.com/contest/1013/problem/A"target="_blank" rel="external nofollow noopener noreferrer">Piles With Stones<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></p>
<p>大致题意就是有 n 堆石头，第一天每堆有一定数目的石头，第二天石头可能被小朋友移动或者带走，求满足题意的两天的石碓；<br>
所以第二天的石头总数不会大于第一天的，所以是 sum1-sum2&gt;=0 即可。<br>
//又只打了一道题，扣了 80 多分。</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">x</span><span class="p">[</span><span class="mi">55</span><span class="p">],</span><span class="n">y</span><span class="p">[</span><span class="mi">55</span><span class="p">],</span><span class="n">n</span><span class="p">,</span><span class="n">s1</span><span class="o">=</span><span class="mi">0</span><span class="p">,</span><span class="n">s2</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">n</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">x</span><span class="p">[</span><span class="n">i</span><span class="p">]);</span>
</span></span><span class="line"><span class="cl">        <span class="n">s1</span><span class="o">+=</span><span class="n">x</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">y</span><span class="p">[</span><span class="n">i</span><span class="p">]);</span>
</span></span><span class="line"><span class="cl">        <span class="n">s2</span><span class="o">+=</span><span class="n">y</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">((</span><span class="n">s1</span><span class="o">-</span><span class="n">s2</span><span class="p">)</span><span class="o">&gt;=</span><span class="mi">0</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;Yes</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="k">else</span> <span class="n">printf</span><span class="p">(</span><span class="s">&#34;No</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>畅通工程-HDU-1232（并查集经典模板）</title><link>https://lruihao.cn/posts/%E7%95%85%E9%80%9A%E5%B7%A5%E7%A8%8B/</link><pubDate>Tue, 31 Jul 2018 11:08:43 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/%E7%95%85%E9%80%9A%E5%B7%A5%E7%A8%8B/</guid><description><![CDATA[<h4 id="并查集入门推荐超有爱的并查集httpsblogcsdnnetniushuai666articledetails6662911">并查集入门推荐：<a href="https://blog.csdn.net/niushuai666/article/details/6662911"target="_blank" rel="external nofollow noopener noreferrer">超有爱的并查集~<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></h4>
<h4 id="题目链接畅通工程httpacmhdueducnshowproblemphppid1232">题目链接：<a href="http://acm.hdu.edu.cn/showproblem.php?pid=1232"target="_blank" rel="external nofollow noopener noreferrer">畅通工程<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></h4>
<h4 id="题意分析">题意分析：</h4>
<p>首先在地图上给你若干个城镇，这些城镇都可以看作点，然后告诉你哪些对城镇之间是有道路直接相连的。最后要解决的是整幅图的连通性问题。比如随意给你两个点，让你判断它们是否连通，或者问你整幅图一共有几个连通分支，也就是被分成了几个互相独立的块。像畅通工程这题，问还需要修几条路，实质就是求有几个连通分支。</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span><span class="lnt">33
</span><span class="lnt">34
</span><span class="lnt">35
</span><span class="lnt">36
</span><span class="lnt">37
</span><span class="lnt">38
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;iostream&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;cstdio&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">pre</span><span class="p">[</span><span class="mi">1010</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">findd</span><span class="p">(</span><span class="kt">int</span> <span class="n">root</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">son</span><span class="p">,</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">son</span><span class="o">=</span><span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">root</span><span class="o">!=</span><span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">        <span class="n">root</span><span class="o">=</span><span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">son</span><span class="o">!=</span><span class="n">root</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">t</span><span class="o">=</span><span class="n">pre</span><span class="p">[</span><span class="n">son</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="n">pre</span><span class="p">[</span><span class="n">son</span><span class="p">]</span><span class="o">=</span><span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">son</span><span class="o">=</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">n</span><span class="p">,</span><span class="n">m</span><span class="p">,</span><span class="n">i</span><span class="p">,</span><span class="n">sum</span><span class="p">,</span><span class="n">r1</span><span class="p">,</span><span class="n">r2</span><span class="p">,</span><span class="n">star</span><span class="p">,</span><span class="n">end1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">n</span><span class="p">)</span><span class="o">&amp;&amp;</span><span class="n">n</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">sum</span><span class="o">=</span><span class="n">n</span><span class="o">-</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="n">pre</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">=</span><span class="n">i</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">m</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">        <span class="k">while</span><span class="p">(</span><span class="n">m</span><span class="o">--</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="n">scanf</span><span class="p">(</span><span class="s">&#34;%d%d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">star</span><span class="p">,</span><span class="o">&amp;</span><span class="n">end1</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">            <span class="n">r1</span><span class="o">=</span><span class="n">findd</span><span class="p">(</span><span class="n">star</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">            <span class="n">r2</span><span class="o">=</span><span class="n">findd</span><span class="p">(</span><span class="n">end1</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">            <span class="k">if</span><span class="p">(</span><span class="n">r1</span><span class="o">!=</span><span class="n">r2</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">                <span class="n">pre</span><span class="p">[</span><span class="n">r1</span><span class="p">]</span><span class="o">=</span><span class="n">r2</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">                <span class="n">sum</span><span class="o">--</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;%d</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">,</span><span class="n">sum</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div><h4 id="基础回顾">基础回顾：</h4>
<h5 id="find-函数找根结点的两种写法如下">find() 函数找根结点的两种写法如下：</h5>
<p>第一种递归：</p>
<div class="highlight" id="id-2"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt">1
</span><span class="lnt">2
</span><span class="lnt">3
</span><span class="lnt">4
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-C" data-lang="C"><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">find</span><span class="p">(</span><span class="kt">int</span> <span class="n">x</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">x</span> <span class="o">==</span> <span class="n">pre</span><span class="p">[</span><span class="n">x</span><span class="p">]</span> <span class="o">?</span> <span class="nl">x</span> <span class="p">:</span> <span class="nf">find</span><span class="p">(</span><span class="n">pre</span><span class="p">[</span><span class="n">x</span><span class="p">]);</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div><p>第二种：</p>
<div class="highlight" id="id-3"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">find</span><span class="p">(</span><span class="kt">int</span> <span class="n">x</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">root</span><span class="p">,</span> <span class="n">temp</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">root</span> <span class="o">=</span> <span class="n">x</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">root</span> <span class="o">!=</span> <span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">        <span class="n">root</span> <span class="o">=</span> <span class="n">pre</span><span class="p">[</span><span class="n">root</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">x</span> <span class="o">!=</span> <span class="n">root</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">    <span class="p">{</span>
</span></span><span class="line"><span class="cl">        <span class="n">temp</span> <span class="o">=</span> <span class="n">pre</span><span class="p">[</span><span class="n">x</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="n">pre</span><span class="p">[</span><span class="n">temp</span><span class="p">]</span> <span class="o">=</span> <span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">x</span> <span class="o">=</span> <span class="n">temp</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="n">root</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div><h5 id="合并函数">合并函数</h5>
<div class="highlight" id="id-4"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt">1
</span><span class="lnt">2
</span><span class="lnt">3
</span><span class="lnt">4
</span><span class="lnt">5
</span><span class="lnt">6
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="line"><span class="cl"><span class="kt">void</span> <span class="nf">join</span><span class="p">(</span><span class="kt">int</span> <span class="n">x</span><span class="p">,</span><span class="kt">int</span> <span class="n">y</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">fx</span><span class="o">=</span><span class="nf">find</span><span class="p">(</span><span class="n">x</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">fy</span><span class="o">=</span><span class="nf">find</span><span class="p">(</span><span class="n">y</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">    <span class="k">if</span><span class="p">(</span><span class="n">fx</span><span class="o">!=</span><span class="n">fy</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">        <span class="n">pre</span><span class="p">[</span><span class="n">fx</span><span class="p">]</span><span class="o">=</span><span class="n">fy</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>牛客练习赛 23</title><link>https://lruihao.cn/posts/%E7%89%9B%E5%AE%A2%E7%BB%83%E4%B9%A0%E8%B5%9B23/</link><pubDate>Fri, 27 Jul 2018 21:56:08 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/%E7%89%9B%E5%AE%A2%E7%BB%83%E4%B9%A0%E8%B5%9B23/</guid><description><![CDATA[<p>两题水过，暴力，找规律。</p>
<h2 id="托米的赌球httpswwwnowcodercomacmcontest156a"><a href="https://www.nowcoder.com/acm/contest/156/A"target="_blank" rel="external nofollow noopener noreferrer">托米的赌球<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></h2>
<h2 id="托米的划分httpswwwnowcodercomacmcontest156b"><a href="https://www.nowcoder.com/acm/contest/156/B"target="_blank" rel="external nofollow noopener noreferrer">托米的划分<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></h2>
<h2 id="a">a</h2>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span><span class="lnt">20
</span><span class="lnt">21
</span><span class="lnt">22
</span><span class="lnt">23
</span><span class="lnt">24
</span><span class="lnt">25
</span><span class="lnt">26
</span><span class="lnt">27
</span><span class="lnt">28
</span><span class="lnt">29
</span><span class="lnt">30
</span><span class="lnt">31
</span><span class="lnt">32
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">c</span><span class="p">[</span><span class="mi">13</span><span class="p">],</span><span class="n">d</span><span class="p">[</span><span class="mi">13</span><span class="p">]</span><span class="o">=</span><span class="p">{</span><span class="mi">100</span><span class="p">,</span><span class="mi">50</span><span class="p">,</span><span class="mi">20</span><span class="p">,</span><span class="mi">10</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">50</span><span class="p">,</span><span class="mi">20</span><span class="p">,</span><span class="mi">10</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="mi">1</span><span class="p">};</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">i</span><span class="p">,</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">t</span><span class="o">--</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">memset</span><span class="p">(</span><span class="n">c</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="k">sizeof</span><span class="p">(</span><span class="n">c</span><span class="p">));</span>
</span></span><span class="line"><span class="cl">        <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">a</span><span class="o">&gt;&gt;</span><span class="n">b</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="mi">7</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="kt">int</span> <span class="n">x</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">a</span><span class="o">&gt;</span><span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="p">]){</span>
</span></span><span class="line"><span class="cl">            <span class="n">x</span><span class="o">=</span><span class="n">a</span><span class="o">/</span><span class="n">d</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">            <span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">+=</span><span class="n">x</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="n">a</span><span class="o">-=</span><span class="n">x</span><span class="o">*</span><span class="n">d</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">7</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="mi">13</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">            <span class="kt">int</span> <span class="n">x</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">b</span><span class="o">&gt;</span><span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="p">]){</span>
</span></span><span class="line"><span class="cl">            <span class="n">x</span><span class="o">=</span><span class="n">b</span><span class="o">/</span><span class="n">d</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">            <span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">+=</span><span class="n">x</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">            <span class="n">b</span><span class="o">-=</span><span class="n">x</span><span class="o">*</span><span class="n">d</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="p">}</span>
</span></span><span class="line"><span class="cl">        <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">c</span><span class="p">[</span><span class="mi">0</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="mi">13</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="s">&#34; &#34;</span><span class="o">&lt;&lt;</span><span class="n">c</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>
</span></span><span class="line"><span class="cl">        <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div><h2 id="b">b</h2>
<p>f(n)=f(n-1)+n-1;</p>
<div class="highlight" id="id-2"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span><span class="lnt">14
</span><span class="lnt">15
</span><span class="lnt">16
</span><span class="lnt">17
</span><span class="lnt">18
</span><span class="lnt">19
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="n">using</span> <span class="n">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">long</span> <span class="kt">long</span> <span class="n">sum</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">(){</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">n</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="kt">int</span> <span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">t</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="k">while</span><span class="p">(</span><span class="n">t</span><span class="o">--</span><span class="p">){</span>
</span></span><span class="line"><span class="cl">        <span class="n">sum</span><span class="o">=</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">cin</span><span class="o">&gt;&gt;</span><span class="n">n</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">if</span><span class="p">(</span><span class="n">n</span><span class="o">==</span><span class="mi">1</span><span class="p">)</span> <span class="n">sum</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="k">for</span><span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">3</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;=</span><span class="n">n</span><span class="p">;</span><span class="n">i</span><span class="o">++</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">            <span class="n">sum</span><span class="o">+=</span><span class="n">i</span><span class="o">-</span><span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">        <span class="n">cout</span><span class="o">&lt;&lt;</span><span class="n">sum</span><span class="o">&lt;&lt;</span><span class="n">endl</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item><item><title>HDU-1495-非常可乐（bfs 模拟倒水 or 数论）</title><link>https://lruihao.cn/posts/hdu-1495/</link><pubDate>Tue, 24 Jul 2018 15:34:00 +0000</pubDate><author>Lruihao</author><guid>https://lruihao.cn/posts/hdu-1495/</guid><description><![CDATA[<p><a href="http://acm.hdu.edu.cn/showproblem.php?pid=1495"target="_blank" rel="external nofollow noopener noreferrer">非常可乐<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></p>
<p>大家一定觉的运动以后喝可乐是一件很惬意的事情，但是 seeyou 却不这么认为。因为每次当 seeyou 买了可乐以后，阿牛就要求和 seeyou 一起分享这一瓶可乐，而且一定要喝的和 seeyou 一样多。但 seeyou 的手中只有两个杯子，它们的容量分别是 N 毫升和 M 毫升 可乐的体积为 S （S&lt;101）毫升　（正好装满一瓶） ，它们三个之间可以相互倒可乐 （都是没有刻度的，且 S==N+M，101 ＞ S ＞ 0，N ＞ 0，M ＞ 0) 。聪明的 ACMER 你们说他们能平分吗？如果能请输出倒可乐的最少的次数，如果不能输出&quot;NO&quot;。</p>
<h3 id="input">Input</h3>
<p>三个整数 : S 可乐的体积 , N 和 M 是两个杯子的容量，以&quot;0 0 0&quot;结束。</p>
<h3 id="output">Output</h3>
<p>如果能平分的话请输出最少要倒的次数，否则输出&quot;NO&quot;。</p>
<h3 id="sample-input">Sample Input</h3>
<pre><code>7 4 3
4 1 3
0 0 0
</code></pre>
<h3 id="sample-output">Sample Output</h3>
<pre><code>NO
3
</code></pre>
<p>模拟一下倒水的过程，一共有三种倒法，a 向 bc，b 向 ac，c 向 ab。（相当于一共六个方向）搜索并记录搜索过的过程就好了。</p>
<div class="highlight" id="id-1"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt">  1
</span><span class="lnt">  2
</span><span class="lnt">  3
</span><span class="lnt">  4
</span><span class="lnt">  5
</span><span class="lnt">  6
</span><span class="lnt">  7
</span><span class="lnt">  8
</span><span class="lnt">  9
</span><span class="lnt"> 10
</span><span class="lnt"> 11
</span><span class="lnt"> 12
</span><span class="lnt"> 13
</span><span class="lnt"> 14
</span><span class="lnt"> 15
</span><span class="lnt"> 16
</span><span class="lnt"> 17
</span><span class="lnt"> 18
</span><span class="lnt"> 19
</span><span class="lnt"> 20
</span><span class="lnt"> 21
</span><span class="lnt"> 22
</span><span class="lnt"> 23
</span><span class="lnt"> 24
</span><span class="lnt"> 25
</span><span class="lnt"> 26
</span><span class="lnt"> 27
</span><span class="lnt"> 28
</span><span class="lnt"> 29
</span><span class="lnt"> 30
</span><span class="lnt"> 31
</span><span class="lnt"> 32
</span><span class="lnt"> 33
</span><span class="lnt"> 34
</span><span class="lnt"> 35
</span><span class="lnt"> 36
</span><span class="lnt"> 37
</span><span class="lnt"> 38
</span><span class="lnt"> 39
</span><span class="lnt"> 40
</span><span class="lnt"> 41
</span><span class="lnt"> 42
</span><span class="lnt"> 43
</span><span class="lnt"> 44
</span><span class="lnt"> 45
</span><span class="lnt"> 46
</span><span class="lnt"> 47
</span><span class="lnt"> 48
</span><span class="lnt"> 49
</span><span class="lnt"> 50
</span><span class="lnt"> 51
</span><span class="lnt"> 52
</span><span class="lnt"> 53
</span><span class="lnt"> 54
</span><span class="lnt"> 55
</span><span class="lnt"> 56
</span><span class="lnt"> 57
</span><span class="lnt"> 58
</span><span class="lnt"> 59
</span><span class="lnt"> 60
</span><span class="lnt"> 61
</span><span class="lnt"> 62
</span><span class="lnt"> 63
</span><span class="lnt"> 64
</span><span class="lnt"> 65
</span><span class="lnt"> 66
</span><span class="lnt"> 67
</span><span class="lnt"> 68
</span><span class="lnt"> 69
</span><span class="lnt"> 70
</span><span class="lnt"> 71
</span><span class="lnt"> 72
</span><span class="lnt"> 73
</span><span class="lnt"> 74
</span><span class="lnt"> 75
</span><span class="lnt"> 76
</span><span class="lnt"> 77
</span><span class="lnt"> 78
</span><span class="lnt"> 79
</span><span class="lnt"> 80
</span><span class="lnt"> 81
</span><span class="lnt"> 82
</span><span class="lnt"> 83
</span><span class="lnt"> 84
</span><span class="lnt"> 85
</span><span class="lnt"> 86
</span><span class="lnt"> 87
</span><span class="lnt"> 88
</span><span class="lnt"> 89
</span><span class="lnt"> 90
</span><span class="lnt"> 91
</span><span class="lnt"> 92
</span><span class="lnt"> 93
</span><span class="lnt"> 94
</span><span class="lnt"> 95
</span><span class="lnt"> 96
</span><span class="lnt"> 97
</span><span class="lnt"> 98
</span><span class="lnt"> 99
</span><span class="lnt">100
</span><span class="lnt">101
</span><span class="lnt">102
</span><span class="lnt">103
</span><span class="lnt">104
</span><span class="lnt">105
</span><span class="lnt">106
</span><span class="lnt">107
</span><span class="lnt">108
</span><span class="lnt">109
</span><span class="lnt">110
</span><span class="lnt">111
</span><span class="lnt">112
</span><span class="lnt">113
</span><span class="lnt">114
</span><span class="lnt">115
</span><span class="lnt">116
</span><span class="lnt">117
</span><span class="lnt">118
</span><span class="lnt">119
</span><span class="lnt">120
</span><span class="lnt">121
</span><span class="lnt">122
</span><span class="lnt">123
</span><span class="lnt">124
</span><span class="lnt">125
</span><span class="lnt">126
</span><span class="lnt">127
</span><span class="lnt">128
</span><span class="lnt">129
</span><span class="lnt">130
</span><span class="lnt">131
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-cpp" data-lang="cpp"><span class="line"><span class="cl"><span class="cp">#include</span><span class="cpf">&lt;bits/stdc++.h&gt;</span><span class="cp">
</span></span></span><span class="line"><span class="cl"><span class="cp"></span><span class="k">using</span> <span class="k">namespace</span> <span class="n">std</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">a</span><span class="p">,</span><span class="n">b</span><span class="p">,</span><span class="n">c</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="n">used</span><span class="p">[</span><span class="mi">111</span><span class="p">][</span><span class="mi">111</span><span class="p">][</span><span class="mi">111</span><span class="p">];</span>
</span></span><span class="line"><span class="cl"><span class="k">struct</span> <span class="nc">node</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">	<span class="kt">int</span> <span class="n">x</span><span class="p">,</span><span class="n">y</span><span class="p">,</span><span class="n">z</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="kt">int</span> <span class="n">step</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span><span class="n">m</span><span class="p">,</span><span class="n">n</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">bfs</span><span class="p">()</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">	<span class="n">queue</span><span class="o">&lt;</span><span class="n">node</span><span class="o">&gt;</span><span class="n">q</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="n">m</span><span class="p">.</span><span class="n">x</span> <span class="o">=</span> <span class="n">a</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="n">m</span><span class="p">.</span><span class="n">y</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="n">m</span><span class="p">.</span><span class="n">z</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="n">m</span><span class="p">.</span><span class="n">step</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="n">used</span><span class="p">[</span><span class="n">a</span><span class="p">][</span><span class="mi">0</span><span class="p">][</span><span class="mi">0</span><span class="p">]</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">	<span class="n">q</span><span class="p">.</span><span class="n">push</span><span class="p">(</span><span class="n">m</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">	<span class="k">while</span> <span class="p">(</span><span class="o">!</span><span class="n">q</span><span class="p">.</span><span class="n">empty</span><span class="p">())</span>
</span></span><span class="line"><span class="cl">	<span class="p">{</span>
</span></span><span class="line"><span class="cl">		<span class="kt">int</span> <span class="n">trans</span><span class="p">;</span>		<span class="c1">//倒水量
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="n">m</span> <span class="o">=</span> <span class="n">q</span><span class="p">.</span><span class="n">front</span><span class="p">();</span>
</span></span><span class="line"><span class="cl">		<span class="n">q</span><span class="p">.</span><span class="n">pop</span><span class="p">();</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="c1">//成功分好的三种情况
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="k">if</span> <span class="p">((</span><span class="n">m</span><span class="p">.</span><span class="n">x</span> <span class="o">==</span> <span class="mi">0</span> <span class="o">&amp;&amp;</span> <span class="n">m</span><span class="p">.</span><span class="n">y</span> <span class="o">==</span> <span class="n">m</span><span class="p">.</span><span class="n">z</span><span class="p">)</span> <span class="o">||</span> <span class="p">(</span><span class="n">m</span><span class="p">.</span><span class="n">y</span> <span class="o">==</span> <span class="mi">0</span> <span class="o">&amp;&amp;</span> <span class="n">m</span><span class="p">.</span><span class="n">x</span> <span class="o">==</span> <span class="n">m</span><span class="p">.</span><span class="n">z</span><span class="p">)</span> <span class="o">||</span> <span class="p">(</span><span class="n">m</span><span class="p">.</span><span class="n">z</span> <span class="o">==</span> <span class="mi">0</span> <span class="o">&amp;&amp;</span> <span class="n">m</span><span class="p">.</span><span class="n">x</span> <span class="o">==</span> <span class="n">m</span><span class="p">.</span><span class="n">y</span><span class="p">))</span>
</span></span><span class="line"><span class="cl">			<span class="k">return</span> <span class="n">m</span><span class="p">.</span><span class="n">step</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">		<span class="c1">//下面开始 6 个搜索（由一个杯子向另外两个倒水）
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>		<span class="k">if</span> <span class="p">(</span><span class="n">m</span><span class="p">.</span><span class="n">x</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">		<span class="p">{</span>
</span></span><span class="line"><span class="cl">			<span class="c1">//第一
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">trans</span> <span class="o">=</span> <span class="n">min</span><span class="p">(</span><span class="n">m</span><span class="p">.</span><span class="n">x</span> <span class="p">,</span> <span class="n">b</span> <span class="o">-</span> <span class="n">m</span><span class="p">.</span><span class="n">y</span><span class="p">);</span><span class="c1">//自己模拟一下倒水过程就知道了
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>				<span class="n">n</span><span class="p">.</span><span class="n">x</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">x</span> <span class="o">-</span> <span class="n">trans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">y</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">y</span> <span class="o">+</span> <span class="n">trans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">z</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">z</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">step</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">step</span> <span class="o">+</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">used</span><span class="p">[</span><span class="n">n</span><span class="p">.</span><span class="n">x</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">y</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">z</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">				<span class="p">{</span>
</span></span><span class="line"><span class="cl">					<span class="n">q</span><span class="p">.</span><span class="n">push</span><span class="p">(</span><span class="n">n</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">					<span class="n">used</span><span class="p">[</span><span class="n">n</span><span class="p">.</span><span class="n">x</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">y</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">z</span><span class="p">]</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">			<span class="c1">//第二
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">trans</span> <span class="o">=</span> <span class="n">min</span><span class="p">(</span><span class="n">m</span><span class="p">.</span><span class="n">x</span> <span class="p">,</span> <span class="n">c</span> <span class="o">-</span> <span class="n">m</span><span class="p">.</span><span class="n">z</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">x</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">x</span> <span class="o">-</span> <span class="n">trans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">y</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">y</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">z</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">z</span> <span class="o">+</span> <span class="n">trans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">step</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">step</span> <span class="o">+</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">used</span><span class="p">[</span><span class="n">n</span><span class="p">.</span><span class="n">x</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">y</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">z</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">				<span class="p">{</span>
</span></span><span class="line"><span class="cl">					<span class="n">q</span><span class="p">.</span><span class="n">push</span><span class="p">(</span><span class="n">n</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">					<span class="n">used</span><span class="p">[</span><span class="n">n</span><span class="p">.</span><span class="n">x</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">y</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">z</span><span class="p">]</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="p">}</span>
</span></span><span class="line"><span class="cl">		<span class="p">}</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="p">(</span><span class="n">m</span><span class="p">.</span><span class="n">y</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">		<span class="p">{</span>
</span></span><span class="line"><span class="cl">			<span class="c1">//第三
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">trans</span> <span class="o">=</span> <span class="n">min</span><span class="p">(</span><span class="n">m</span><span class="p">.</span><span class="n">y</span> <span class="p">,</span> <span class="n">a</span> <span class="o">-</span> <span class="n">m</span><span class="p">.</span><span class="n">x</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">x</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">x</span> <span class="o">+</span> <span class="n">trans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">y</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">y</span> <span class="o">-</span> <span class="n">trans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">z</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">z</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">step</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">step</span> <span class="o">+</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">used</span><span class="p">[</span><span class="n">n</span><span class="p">.</span><span class="n">x</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">y</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">z</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">				<span class="p">{</span>
</span></span><span class="line"><span class="cl">					<span class="n">used</span><span class="p">[</span><span class="n">n</span><span class="p">.</span><span class="n">x</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">y</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">z</span><span class="p">]</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">					<span class="n">q</span><span class="p">.</span><span class="n">push</span><span class="p">(</span><span class="n">n</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">				<span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">			<span class="c1">//第四
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">trans</span> <span class="o">=</span> <span class="n">min</span><span class="p">(</span><span class="n">m</span><span class="p">.</span><span class="n">y</span> <span class="p">,</span> <span class="n">c</span> <span class="o">-</span> <span class="n">m</span><span class="p">.</span><span class="n">z</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">x</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">x</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">y</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">y</span> <span class="o">-</span> <span class="n">trans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">z</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">z</span> <span class="o">+</span> <span class="n">trans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">step</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">step</span> <span class="o">+</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">used</span><span class="p">[</span><span class="n">n</span><span class="p">.</span><span class="n">x</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">y</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">z</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">				<span class="p">{</span>
</span></span><span class="line"><span class="cl">					<span class="n">used</span><span class="p">[</span><span class="n">n</span><span class="p">.</span><span class="n">x</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">y</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">z</span><span class="p">]</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">					<span class="n">q</span><span class="p">.</span><span class="n">push</span><span class="p">(</span><span class="n">n</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">				<span class="p">}</span>
</span></span><span class="line"><span class="cl">		<span class="p">}</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="p">(</span><span class="n">m</span><span class="p">.</span><span class="n">z</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">		<span class="p">{</span>
</span></span><span class="line"><span class="cl">			<span class="c1">//第五
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">trans</span> <span class="o">=</span> <span class="n">min</span><span class="p">(</span><span class="n">m</span><span class="p">.</span><span class="n">z</span> <span class="p">,</span> <span class="n">a</span> <span class="o">-</span> <span class="n">m</span><span class="p">.</span><span class="n">x</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">x</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">x</span> <span class="o">+</span> <span class="n">trans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">y</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">y</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">z</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">z</span> <span class="o">-</span> <span class="n">trans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">step</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">step</span> <span class="o">+</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">used</span><span class="p">[</span><span class="n">n</span><span class="p">.</span><span class="n">x</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">y</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">z</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">				<span class="p">{</span>
</span></span><span class="line"><span class="cl">					<span class="n">used</span><span class="p">[</span><span class="n">n</span><span class="p">.</span><span class="n">x</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">y</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">z</span><span class="p">]</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">					<span class="n">q</span><span class="p">.</span><span class="n">push</span><span class="p">(</span><span class="n">n</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">				<span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">			<span class="c1">//第六
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">trans</span> <span class="o">=</span> <span class="n">min</span><span class="p">(</span><span class="n">m</span><span class="p">.</span><span class="n">z</span> <span class="p">,</span> <span class="n">b</span> <span class="o">-</span> <span class="n">m</span><span class="p">.</span><span class="n">y</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">x</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">x</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">y</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">y</span> <span class="o">+</span> <span class="n">trans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">z</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">z</span> <span class="o">-</span> <span class="n">trans</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="n">n</span><span class="p">.</span><span class="n">step</span> <span class="o">=</span> <span class="n">m</span><span class="p">.</span><span class="n">step</span> <span class="o">+</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">used</span><span class="p">[</span><span class="n">n</span><span class="p">.</span><span class="n">x</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">y</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">z</span><span class="p">])</span>
</span></span><span class="line"><span class="cl">				<span class="p">{</span>
</span></span><span class="line"><span class="cl">					<span class="n">q</span><span class="p">.</span><span class="n">push</span><span class="p">(</span><span class="n">n</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">					<span class="n">used</span><span class="p">[</span><span class="n">n</span><span class="p">.</span><span class="n">x</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">y</span><span class="p">][</span><span class="n">n</span><span class="p">.</span><span class="n">z</span><span class="p">]</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
</span></span><span class="line"><span class="cl">				<span class="p">}</span>
</span></span><span class="line"><span class="cl">		<span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span>
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl"><span class="kt">int</span> <span class="nf">main</span><span class="p">()</span>
</span></span><span class="line"><span class="cl"><span class="p">{</span>
</span></span><span class="line"><span class="cl">	<span class="k">while</span> <span class="p">(</span><span class="o">~</span><span class="n">scanf</span> <span class="p">(</span><span class="s">&#34;%d %d %d&#34;</span><span class="p">,</span><span class="o">&amp;</span><span class="n">a</span><span class="p">,</span><span class="o">&amp;</span><span class="n">b</span><span class="p">,</span><span class="o">&amp;</span><span class="n">c</span><span class="p">)</span> <span class="o">&amp;&amp;</span> <span class="p">(</span><span class="n">a</span> <span class="o">||</span> <span class="n">b</span> <span class="o">||</span> <span class="n">c</span><span class="p">))</span>
</span></span><span class="line"><span class="cl">	<span class="p">{</span>
</span></span><span class="line"><span class="cl">		<span class="k">if</span> <span class="p">(</span><span class="n">a</span><span class="o">&amp;</span><span class="mi">1</span><span class="p">)</span>		<span class="c1">//先简单的剪枝一下，奇数肯定不能平分
</span></span></span><span class="line"><span class="cl"><span class="c1"></span>			<span class="n">printf</span> <span class="p">(</span><span class="s">&#34;NO</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">		<span class="k">else</span>
</span></span><span class="line"><span class="cl">		<span class="p">{</span>
</span></span><span class="line"><span class="cl">			<span class="n">memset</span> <span class="p">(</span><span class="n">used</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="k">sizeof</span> <span class="p">(</span><span class="n">used</span><span class="p">));</span>
</span></span><span class="line"><span class="cl">			<span class="kt">int</span> <span class="n">ans</span> <span class="o">=</span> <span class="n">bfs</span><span class="p">();</span>
</span></span><span class="line"><span class="cl">			<span class="k">if</span> <span class="p">(</span><span class="n">ans</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">				<span class="n">printf</span> <span class="p">(</span><span class="s">&#34;%d</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">,</span><span class="n">ans</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">			<span class="k">else</span>
</span></span><span class="line"><span class="cl">				<span class="n">printf</span> <span class="p">(</span><span class="s">&#34;NO</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
</span></span><span class="line"><span class="cl">		<span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="p">}</span>
</span></span><span class="line"><span class="cl">	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre></td></tr></table>
</div>
</div><p>然后杭电上讨论板子上提供一种数论题解，<del>但是数据存在一点问题，只不过有些数据好像不对；比如： 10 6 5 的结果应该是 1 而不是 9</del>， 也提示我们多维思考同一个问题！</p>
<p><a href="https://blog.csdn.net/V5ZSQ/article/details/52097459"target="_blank" rel="external nofollow noopener noreferrer">数论推导<i class="fa-solid fa-external-link-alt fa-fw fa-xs ms-1 text-secondary" aria-hidden="true"></i></a></p>
<div class="highlight" id="id-2"><div class="chroma">
<table class="lntable"><tr><td class="lntd">
<pre tabindex="0" class="chroma"><code><span class="lnt"> 1
</span><span class="lnt"> 2
</span><span class="lnt"> 3
</span><span class="lnt"> 4
</span><span class="lnt"> 5
</span><span class="lnt"> 6
</span><span class="lnt"> 7
</span><span class="lnt"> 8
</span><span class="lnt"> 9
</span><span class="lnt">10
</span><span class="lnt">11
</span><span class="lnt">12
</span><span class="lnt">13
</span></code></pre></td>
<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-fallback" data-lang="fallback"><span class="line"><span class="cl">#include&lt;bits/stdc++.h&gt;
</span></span><span class="line"><span class="cl">using namespace std;
</span></span><span class="line"><span class="cl">
</span></span><span class="line"><span class="cl">int main(){
</span></span><span class="line"><span class="cl">    int s,n,m;
</span></span><span class="line"><span class="cl">    while(cin&gt;&gt;s&gt;&gt;n&gt;&gt;m,s+n+m){
</span></span><span class="line"><span class="cl">        s/=__gcd(n,m);
</span></span><span class="line"><span class="cl">        if(s&amp;1)//奇数
</span></span><span class="line"><span class="cl">            cout&lt;&lt;&#34;NO\n&#34;;
</span></span><span class="line"><span class="cl">        else cout&lt;&lt;s-1&lt;&lt;endl;
</span></span><span class="line"><span class="cl">    }
</span></span><span class="line"><span class="cl">    return 0;
</span></span><span class="line"><span class="cl">}</span></span></code></pre></td></tr></table>
</div>
</div>]]></description></item></channel></rss>