blog/content/post/2008/04/24/2008-04-24-00000883.md

---
title: アルゴリズム
author: kazu634
date: 2008-04-24
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categories:
  - つれづれ

---
<div class="section">
<p>
    　研修で簡単なアルゴリズムを勉強している。まだ前半なのでフローチャートを書いているだけ。これだとちょっとふぬけてしまうので、勉強したフローチャートをCで書いてみた。
</p>
  
<h4>
    値の交換
</h4>
  
<pre class="syntax-highlight">
<span class="synPreProc">#include </span><span class="synConstant">&#60;stdio.h&#62;</span>
<span class="synType">int</span> main(<span class="synType">void</span>);
<span class="synType">int</span> main(<span class="synType">void</span>)
{
<span class="synType">int</span> x, y, z;
x = <span class="synConstant">10</span>;
y = <span class="synConstant">15</span>;
printf (<span class="synConstant">&#34;Before Swap:</span><span class="synSpecial">\n</span><span class="synConstant">&#34;</span>);
printf (<span class="synConstant">&#34;x: </span><span class="synSpecial">%2d</span><span class="synConstant"> </span><span class="synSpecial">\n</span><span class="synConstant">&#34;</span>, x);
printf (<span class="synConstant">&#34;y: </span><span class="synSpecial">%2d</span><span class="synConstant"> </span><span class="synSpecial">\n</span><span class="synConstant">&#34;</span>, y);
z = x;
x = y;
y = z;
printf (<span class="synConstant">&#34;</span><span class="synSpecial">\n</span><span class="synConstant">After Swap:</span><span class="synSpecial">\n</span><span class="synConstant">&#34;</span>);
printf (<span class="synConstant">&#34;x: </span><span class="synSpecial">%2d</span><span class="synConstant"> </span><span class="synSpecial">\n</span><span class="synConstant">&#34;</span>, x);
printf (<span class="synConstant">&#34;y: </span><span class="synSpecial">%2d</span><span class="synConstant"> </span><span class="synSpecial">\n</span><span class="synConstant">&#34;</span>, y);
}
</pre>
  
<h4>
    三つの値の中から大きな数値を取り出す
</h4>
  
<pre class="syntax-highlight">
<span class="synPreProc">#include </span><span class="synConstant">&#60;stdio.h&#62;</span>
<span class="synType">int</span> main(<span class="synType">void</span>);
<span class="synType">int</span> main(<span class="synType">void</span>)
{
<span class="synType">int</span> x, y, z;
<span class="synType">int</span> max;
x = <span class="synConstant">13</span>;
y = <span class="synConstant">45</span>;
z = <span class="synConstant">30</span>;
max = x;
<span class="synStatement">if</span> (max &#60;= y) {
max = y;
}
<span class="synStatement">if</span> (max &#60;= z) {
max = z;
}
printf (<span class="synConstant">&#34;max: </span><span class="synSpecial">%2d\n</span><span class="synConstant">&#34;</span>, max);
}
</pre>
  
<h4>
    1～3までの和を求める
</h4>
  
<pre class="syntax-highlight">
<span class="synPreProc">#include </span><span class="synConstant">&#60;stdio.h&#62;</span>
<span class="synType">int</span> main(<span class="synType">void</span>);
<span class="synType">int</span> main(<span class="synType">void</span>)
{
<span class="synType">int</span> i, sum;
sum = <span class="synConstant"></span>;
<span class="synStatement">for</span> (i = <span class="synConstant"></span>;i &#60;= <span class="synConstant">3</span>;i++) {
sum = sum + i;
}
printf (<span class="synConstant">&#34;sum is: </span><span class="synSpecial">%2d\n</span><span class="synConstant">&#34;</span>, sum);
}
</pre>
  
<h4>
    配列の要素をすべて足す
</h4>
  
<p>
    　冗長だ。配列の要素数を取得できる命令はこれから自習するから、その時にまた振り返ろう。
</p>
  
<pre class="syntax-highlight">
<span class="synPreProc">#include </span><span class="synConstant">&#60;stdio.h&#62;</span>
<span class="synType">int</span> main(<span class="synType">void</span>);
<span class="synType">int</span> main(<span class="synType">void</span>)
{
<span class="synType">int</span> i[<span class="synConstant">5</span>], sum, j;
i[<span class="synConstant"></span>] = <span class="synConstant">10</span>;
i[<span class="synConstant">1</span>] = <span class="synConstant">20</span>;
i[<span class="synConstant">2</span>] = <span class="synConstant">30</span>;
i[<span class="synConstant">3</span>] = <span class="synConstant">40</span>;
i[<span class="synConstant">4</span>] = <span class="synConstant">50</span>;
sum = <span class="synConstant"></span>;
<span class="synStatement">for</span> (j = <span class="synConstant"></span>;j &#60;= <span class="synConstant">4</span>; j++) {
sum = sum + i[j];
}
printf (<span class="synConstant">&#34;</span><span class="synSpecial">%2d\n</span><span class="synConstant">&#34;</span>, sum);
}
</pre>
</div>