2019-03-31 11:00:21 +00:00
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title: 研修であつかったアルゴリズムを黙々と書くよ
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author: kazu634
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date: 2008-05-10
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wordtwit_post_info:
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- 'O:8:"stdClass":13:{s:6:"manual";b:0;s:11:"tweet_times";i:1;s:5:"delay";i:0;s:7:"enabled";i:1;s:10:"separation";s:2:"60";s:7:"version";s:3:"3.7";s:14:"tweet_template";b:0;s:6:"status";i:2;s:6:"result";a:0:{}s:13:"tweet_counter";i:2;s:13:"tweet_log_ids";a:1:{i:0;i:3999;}s:9:"hash_tags";a:0:{}s:8:"accounts";a:1:{i:0;s:7:"kazu634";}}'
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categories:
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- C
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- Programming
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---
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<div class="section">
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<p>
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随時追加していく。
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</p>
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<h4>
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二分探索
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</h4>
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<pre class="syntax-highlight">
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<span class="synPreProc">#include </span><span class="synConstant"><stdio.h></span>
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<span class="synType">int</span> main(<span class="synType">void</span>);
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<span class="synType">int</span> bin_search(<span class="synType">const</span> <span class="synType">int</span> a[], <span class="synType">int</span> num_a, <span class="synType">int</span> key);
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<span class="synType">int</span> bin_search(<span class="synType">const</span> <span class="synType">int</span> a[], <span class="synType">int</span> num_a, <span class="synType">int</span> key)
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{
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<span class="synType">int</span> pof = <span class="synConstant">1</span>; <span class="synComment">/* 二分探索の始点(Position of First) */</span>
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<span class="synType">int</span> pol = num_a - <span class="synConstant">1</span>; <span class="synComment">/* 二分探索の終点(Position of Last) */</span>
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<span class="synType">int</span> poc = (pof + pol) / <span class="synConstant">2</span>; <span class="synComment">/* 二分探索の中央(Position of Center)*/</span>
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<span class="synType">int</span> p = -<span class="synConstant">1</span>; <span class="synComment">/* keyが発見された要素の添え字 */</span>
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<span class="synStatement">while</span> (p == -<span class="synConstant">1</span> && pof <= pol) {
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<span class="synComment">/* 中央の値がkeyと一致した！ */</span>
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<span class="synStatement">if</span> (a[poc] == key) {
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p = poc;
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<span class="synStatement">return</span>(p);
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} <span class="synStatement">else</span> <span class="synStatement">if</span> (a[poc] < key) {
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<span class="synComment">/* 中央の値よりもkeyの値の方が大きい */</span>
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pof = poc + <span class="synConstant">1</span>;
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poc = (pof + pol) / <span class="synConstant">2</span>;
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} <span class="synStatement">else</span> <span class="synStatement">if</span> (key < a[poc]) {
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<span class="synComment">/* keyの値よりも中央の値の方が大きい*/</span>
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pol = poc - <span class="synConstant">1</span>;
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poc = (pof + pol) / <span class="synConstant">2</span>;
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}
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}
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<span class="synStatement">return</span>(p);
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}
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<span class="synType">int</span> main(<span class="synType">void</span>)
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{
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<span class="synType">int</span> array[<span class="synConstant">8</span>] = {<span class="synConstant"></span>, <span class="synConstant">10</span>, <span class="synConstant">20</span>, <span class="synConstant">30</span>, <span class="synConstant">40</span>, <span class="synConstant">50</span>, <span class="synConstant">60</span>, <span class="synConstant">70</span>};
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<span class="synType">int</span> num_array = <span class="synStatement">sizeof</span>(array) / <span class="synStatement">sizeof</span>(array[<span class="synConstant"></span>]);
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printf (<span class="synConstant">"</span><span class="synSpecial">%d\n</span><span class="synConstant">"</span>, bin_search(array, num_array, <span class="synConstant">100</span>));
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<span class="synStatement">return</span>(<span class="synConstant"></span>);
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}
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</pre>
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<h4>
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基本選択法
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</h4>
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<p>
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基本選択法は整列対象のデータの中から一番大きいデータを選び出して、整列対象の最後のデータと交換する。そして整列対象の最後のデータをのぞいて、もう一度同じ処理を行う。この走査を整列対象のデータ数が残り一個になるまで繰り返して行うことによって、値が大きなデータを次第に右端の方に移していく方法である。
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</p>
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<pre class="syntax-highlight">
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<span class="synPreProc">#include </span><span class="synConstant"><stdio.h></span>
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<span class="synType">int</span> main(<span class="synType">void</span>);
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<span class="synComment">/* sortだとすでに使われてそうだから適当に名前付け */</span>
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<span class="synType">void</span> m_sort(<span class="synType">int</span> a[], <span class="synType">const</span> <span class="synType">int</span> num_a);
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<span class="synType">void</span> prt_int_array(<span class="synType">const</span> <span class="synType">int</span> a[], <span class="synType">int</span> num_a);
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<span class="synType">void</span> prt_int_array(<span class="synType">const</span> <span class="synType">int</span> a[], <span class="synType">int</span> num_a)
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{
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<span class="synType">int</span> i;
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<span class="synStatement">for</span> (i = <span class="synConstant"></span>;i < num_a;i++) {
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printf (<span class="synConstant">"</span><span class="synSpecial">%d</span><span class="synConstant">, "</span>, a[i]);
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}
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printf (<span class="synConstant">"</span><span class="synSpecial">\n</span><span class="synConstant">"</span>);
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}
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<span class="synType">void</span> m_sort(<span class="synType">int</span> a[], <span class="synType">const</span> <span class="synType">int</span> num_a)
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{
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<span class="synType">int</span> curwork = num_a - <span class="synConstant">1</span>; <span class="synComment">/* 確定させたい配列の添え字 */</span>
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<span class="synType">int</span> max_a_num; <span class="synComment">/* 未確定の要素の中で最大値の要素の添え字 */</span>
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<span class="synType">int</span> i, tmp;
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<span class="synComment">/* 確定させたい配列の要素数が 2 になるまで */</span>
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<span class="synStatement">while</span> (<span class="synConstant"></span> < curwork) {
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prt_int_array(a, num_a);
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<span class="synComment">/* とりあえず確定させたい配列の添え字を最大値と仮定 */</span>
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max_a_num = curwork;
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printf (<span class="synConstant">"確定させたい要素の添え字: </span><span class="synSpecial">%d\n</span><span class="synConstant">"</span>, curwork);
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printf (<span class="synConstant">"0... </span><span class="synSpecial">%d</span><span class="synConstant"> までの範囲を探索するよ。</span><span class="synSpecial">\n</span><span class="synConstant">"</span>, curwork - <span class="synConstant">1</span>);
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<span class="synComment">/* i を「確定させたい要素の添え字 - 1」までまわす */</span>
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<span class="synStatement">for</span> (i = <span class="synConstant"></span>;i < curwork;i++) {
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<span class="synComment">/* それまでの最大値よりもa[i]が大きければ */</span>
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<span class="synStatement">if</span> (a[max_a_num] < a[i]) {
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printf (<span class="synConstant">"a[</span><span class="synSpecial">%d</span><span class="synConstant">] < a[</span><span class="synSpecial">%i</span><span class="synConstant">]</span><span class="synSpecial">\n</span><span class="synConstant">"</span>, max_a_num, i);
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<span class="synComment">/* 最大値の要素の添え字を max_a_num に代入 */</span>
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max_a_num = i;
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}
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}
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printf (<span class="synConstant">"Change </span><span class="synSpecial">%d</span><span class="synConstant">(a[</span><span class="synSpecial">%d</span><span class="synConstant">]) --> </span><span class="synSpecial">%d</span><span class="synConstant">(a[</span><span class="synSpecial">%d</span><span class="synConstant">])</span><span class="synSpecial">\n\n</span><span class="synConstant">"</span>, a[max_a_num], max_a_num, a[curwork], curwork);
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<span class="synComment">/* 最大値を a[curwork] に代入 */</span>
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tmp = a[curwork];
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a[curwork] = a[max_a_num];
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a[max_a_num] = tmp;
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curwork--;
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}
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}
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<span class="synType">int</span> main(<span class="synType">void</span>)
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{
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<span class="synType">int</span> array[<span class="synConstant">8</span>] = {<span class="synConstant">100</span>, <span class="synConstant">95</span>, <span class="synConstant">900</span>, <span class="synConstant">85</span>, <span class="synConstant">9980</span>, <span class="synConstant">795</span>, <span class="synConstant">70</span>, <span class="synConstant">695</span>};
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<span class="synType">int</span> num_array = <span class="synStatement">sizeof</span>(array) / <span class="synStatement">sizeof</span>(array[<span class="synConstant"></span>]);
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m_sort(array, num_array);
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prt_int_array(array, num_array);
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<span class="synStatement">return</span>(<span class="synConstant"></span>);
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}
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</pre>
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<h4>
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バブルソート
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</h4>
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<pre class="syntax-highlight">
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<span class="synPreProc">#include </span><span class="synConstant"><stdio.h></span>
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<span class="synType">int</span> main(<span class="synType">void</span>);
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<span class="synType">void</span> bubble_sort(<span class="synType">int</span> a[], <span class="synType">const</span> <span class="synType">int</span> num_a);
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<span class="synType">void</span> prt_int_array(<span class="synType">const</span> <span class="synType">int</span> a[], <span class="synType">int</span> num_a);
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<span class="synType">void</span> prt_int_array(<span class="synType">const</span> <span class="synType">int</span> a[], <span class="synType">int</span> num_a)
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{
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<span class="synType">int</span> i;
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<span class="synStatement">for</span> (i = <span class="synConstant"></span>;i < num_a;i++) {
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printf (<span class="synConstant">"</span><span class="synSpecial">%d</span><span class="synConstant">, "</span>, a[i]);
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}
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printf (<span class="synConstant">"</span><span class="synSpecial">\n</span><span class="synConstant">"</span>);
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}
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<span class="synType">void</span> bubble_sort(<span class="synType">int</span> a[], <span class="synType">const</span> <span class="synType">int</span> num_a)
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{
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<span class="synType">int</span> curwork = num_a - <span class="synConstant">1</span>; <span class="synComment">/* 確定させたい配列の添え字 */</span>
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<span class="synType">int</span> i, tmp;
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<span class="synComment">/* 確定させたい配列の要素数が 2 になるまで */</span>
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<span class="synStatement">while</span> (<span class="synConstant"></span> < curwork) {
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prt_int_array(a, num_a);
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<span class="synComment">/* curwork - 1までずっとiの値を変化させる */</span>
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<span class="synStatement">for</span> (i = <span class="synConstant"></span>;i < curwork;i++) {
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<span class="synComment">/* a[i] よりも a[i+1] が小さければ交換 */</span>
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<span class="synStatement">if</span> (a[i+<span class="synConstant">1</span>] < a[i]) {
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tmp = a[i];
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a[i] = a[i+<span class="synConstant">1</span>];
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a[i+<span class="synConstant">1</span>] = tmp;
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}
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}
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curwork--;
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}
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}
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<span class="synType">int</span> main(<span class="synType">void</span>)
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{
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<span class="synType">int</span> array[<span class="synConstant">8</span>] = {<span class="synConstant">100</span>, <span class="synConstant">95</span>, <span class="synConstant">900</span>, <span class="synConstant">85</span>, <span class="synConstant">9980</span>, <span class="synConstant">795</span>, <span class="synConstant">70</span>, <span class="synConstant">695</span>};
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<span class="synType">int</span> num_array = <span class="synStatement">sizeof</span>(array) / <span class="synStatement">sizeof</span>(array[<span class="synConstant"></span>]);
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bubble_sort(array, num_array);
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prt_int_array(array, num_array);
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<span class="synStatement">return</span>(<span class="synConstant"></span>);
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}
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</pre>
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<h4>
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基本挿入法
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</h4>
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<pre class="syntax-highlight">
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<span class="synPreProc">#include </span><span class="synConstant"><stdio.h></span>
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<span class="synType">int</span> main(<span class="synType">void</span>);
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<span class="synType">void</span> m__sort(<span class="synType">int</span> a[], <span class="synType">const</span> <span class="synType">int</span> num_a);
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<span class="synType">void</span> prt_int_array(<span class="synType">const</span> <span class="synType">int</span> a[], <span class="synType">int</span> num_a);
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<span class="synType">void</span> prt_int_array(<span class="synType">const</span> <span class="synType">int</span> a[], <span class="synType">int</span> num_a)
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{
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<span class="synType">int</span> i;
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<span class="synStatement">for</span> (i = <span class="synConstant"></span>;i < num_a;i++) {
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printf (<span class="synConstant">"</span><span class="synSpecial">%d</span><span class="synConstant">, "</span>, a[i]);
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}
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printf (<span class="synConstant">"</span><span class="synSpecial">\n</span><span class="synConstant">"</span>);
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}
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<span class="synType">void</span> m_sort(<span class="synType">int</span> a[], <span class="synType">const</span> <span class="synType">int</span> num_a)
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{
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<span class="synType">int</span> arranged = <span class="synConstant"></span>; <span class="synComment">/* 整列済みの最終要素の添え字 */</span>
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<span class="synType">int</span> curwork = <span class="synConstant">1</span>; <span class="synComment">/* 追加データ要素の添え字 */</span>
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<span class="synType">int</span> i, tmp;
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<span class="synComment">/* 最後まで整列するまで */</span>
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<span class="synStatement">while</span> (arranged < num_a - <span class="synConstant">1</span>) {
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printf (<span class="synConstant">"</span><span class="synSpecial">%d</span><span class="synConstant"> まで整列済み。 a[</span><span class="synSpecial">%d</span><span class="synConstant">] を追加データと考えるよ。</span><span class="synSpecial">\n</span><span class="synConstant">"</span>, arranged, curwork);
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printf (<span class="synConstant">"</span><span class="synSpecial">%d</span><span class="synConstant"> ... </span><span class="synSpecial">%d</span><span class="synConstant"> までを </span><span class="synSpecial">%d</span><span class="synConstant"> と比較するよ！</span><span class="synSpecial">\n</span><span class="synConstant">"</span>, <span class="synConstant"></span>, arranged, a[curwork]);
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prt_int_array(a, num_a);
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printf (<span class="synConstant">"</span><span class="synSpecial">\n</span><span class="synConstant">"</span>);
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<span class="synComment">/* 追加データまで走査する */</span>
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<span class="synStatement">for</span> (i = curwork;<span class="synConstant"></span> < i;i--) {
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<span class="synComment">/* もし右側の要素が左側よりも小さければ交換する */</span>
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<span class="synStatement">if</span> (a[i] < a[i-<span class="synConstant">1</span>]) {
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tmp = a[i-<span class="synConstant">1</span>];
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a[i-<span class="synConstant">1</span>] = a[i];
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a[i] = tmp;
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}
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}
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<span class="synComment">/* 整列済みの添え字と追加データの添え字をインクリメント */</span>
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arranged++;
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curwork++;
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}
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}
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<span class="synType">int</span> main(<span class="synType">void</span>)
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{
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<span class="synType">int</span> array[<span class="synConstant">8</span>] = {<span class="synConstant">100</span>, <span class="synConstant">95</span>, <span class="synConstant">900</span>, <span class="synConstant">85</span>, <span class="synConstant">9980</span>, <span class="synConstant">795</span>, <span class="synConstant">70</span>, <span class="synConstant">695</span>};
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<span class="synType">int</span> num_array = <span class="synStatement">sizeof</span>(array) / <span class="synStatement">sizeof</span>(array[<span class="synConstant"></span>]);
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m_sort(array, num_array);
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prt_int_array(array, num_array);
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<span class="synStatement">return</span>(<span class="synConstant"></span>);
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}
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</pre>
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2019-04-02 16:06:15 +00:00
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</div>
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