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krahets
2023-09-17 01:11:45 +08:00
parent 8b99ac6930
commit 830dc9e326
15 changed files with 169 additions and 120 deletions

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@@ -3637,7 +3637,7 @@
<p>运行时间可以直观且准确地反映算法的效率。如果我们想要准确预估一段代码的运行时间,应该如何操作呢?</p>
<ol>
<li><strong>确定运行平台</strong>,包括硬件配置、编程语言、系统环境等,这些因素都会影响代码的运行效率。</li>
<li><strong>评估各种计算操作所需的运行时间</strong>,例如加法操作 <code>+</code> 需要 1 ns乘法操作 <code>*</code> 需要 10 ns打印操作 <code>print()</code> 需要 5 ns 等。</li>
<li><strong>评估各种计算操作所需的运行时间</strong>,例如加法操作 <code>+</code> 需要 1 ns ,乘法操作 <code>*</code> 需要 10 ns ,打印操作 <code>print()</code> 需要 5 ns 等。</li>
<li><strong>统计代码中所有的计算操作</strong>,并将所有操作的执行时间求和,从而得到运行时间。</li>
</ol>
<p>例如在以下代码中,输入数据大小为 <span class="arithmatex">\(n\)</span> </p>
@@ -6519,7 +6519,7 @@ n! = n \times (n - 1) \times (n - 2) \times \dots \times 2 \times 1
<div class="tabbed-block">
<div class="highlight"><span class="filename">worst_best_time_complexity.c</span><pre><span></span><code><a id="__codelineno-190-1" name="__codelineno-190-1" href="#__codelineno-190-1"></a><span class="cm">/* 生成一个数组,元素为 { 1, 2, ..., n },顺序被打乱 */</span>
<a id="__codelineno-190-2" name="__codelineno-190-2" href="#__codelineno-190-2"></a><span class="kt">int</span><span class="w"> </span><span class="o">*</span><span class="nf">randomNumbers</span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">n</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<a id="__codelineno-190-3" name="__codelineno-190-3" href="#__codelineno-190-3"></a><span class="w"> </span><span class="c1">// 分配堆区内存(创建一维可变长数组:数组中元素数量为n元素类型为int</span>
<a id="__codelineno-190-3" name="__codelineno-190-3" href="#__codelineno-190-3"></a><span class="w"> </span><span class="c1">// 分配堆区内存(创建一维可变长数组:数组中元素数量为 n ,元素类型为 int </span>
<a id="__codelineno-190-4" name="__codelineno-190-4" href="#__codelineno-190-4"></a><span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="o">*</span><span class="n">nums</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="o">*</span><span class="p">)</span><span class="n">malloc</span><span class="p">(</span><span class="n">n</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="k">sizeof</span><span class="p">(</span><span class="kt">int</span><span class="p">));</span>
<a id="__codelineno-190-5" name="__codelineno-190-5" href="#__codelineno-190-5"></a><span class="w"> </span><span class="c1">// 生成数组 nums = { 1, 2, 3, ..., n }</span>
<a id="__codelineno-190-6" name="__codelineno-190-6" href="#__codelineno-190-6"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">&lt;</span><span class="w"> </span><span class="n">n</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="o">++</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>