Project Notes

Number of 1 Bits

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Description

tab: English
 
<p>Given a positive integer <code>n</code>, write a function that returns the number of <span data-keyword="set-bit">set bits</span> in its binary representation (also known as the <a href="http://en.wikipedia.org/wiki/Hamming_weight" target="_blank">Hamming weight</a>).</p>
 
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
 
<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">n = 11</span></p>
 
<p><strong>Output:</strong> <span class="example-io">3</span></p>
 
<p><strong>Explanation:</strong></p>
 
<p>The input binary string <strong>1011</strong> has a total of three set bits.</p>
</div>
 
<p><strong class="example">Example 2:</strong></p>
 
<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">n = 128</span></p>
 
<p><strong>Output:</strong> <span class="example-io">1</span></p>
 
<p><strong>Explanation:</strong></p>
 
<p>The input binary string <strong>10000000</strong> has a total of one set bit.</p>
</div>
 
<p><strong class="example">Example 3:</strong></p>
 
<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">n = 2147483645</span></p>
 
<p><strong>Output:</strong> <span class="example-io">30</span></p>
 
<p><strong>Explanation:</strong></p>
 
<p>The input binary string <strong>1111111111111111111111111111101</strong> has a total of thirty set bits.</p>
</div>
 
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>
 
<ul>
	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
</ul>
 
<p>&nbsp;</p>
<strong>Follow up:</strong> If this function is called many times, how would you optimize it?
 
 
---
 
[submissions](https://leetcode.com/problems/number-of-1-bits/submissions/) | [solutions](https://leetcode.com/problems/number-of-1-bits/solutions/)
 
 
tab: 中文
 
<p>给定一个正整数 <code>n</code>，编写一个函数，获取一个正整数的二进制形式并返回其二进制表达式中 <span data-keyword="set-bit">设置位</span> 的个数（也被称为<a href="https://baike.baidu.com/item/%E6%B1%89%E6%98%8E%E9%87%8D%E9%87%8F" target="_blank">汉明重量</a>）。</p>
 
<p>&nbsp;</p>
 
<p><strong>示例 1：</strong></p>
 
<pre>
<strong>输入：</strong>n = 11
<strong>输出：</strong>3
<strong>解释：</strong>输入的二进制串 <code><strong>1011</strong>&nbsp;中，共有 3 个设置位。</code>
</pre>
 
<p><strong>示例 2：</strong></p>
 
<pre>
<strong>输入：</strong>n = 128
<strong>输出：</strong>1
<strong>解释：</strong>输入的二进制串 <strong>10000000</strong>&nbsp;中，共有 1 个设置位。
</pre>
 
<p><strong>示例 3：</strong></p>
 
<pre>
<strong>输入：</strong>n = 2147483645
<strong>输出：</strong>30
<strong>解释：</strong>输入的二进制串 <strong>1111111111111111111111111111101</strong> 中，共有 30 个设置位。</pre>
 
<p>&nbsp;</p>
 
<p><strong>提示：</strong></p>
 
<ul>
	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
</ul>
 
<ul>
</ul>
 
<p>&nbsp;</p>
 
<p><strong>进阶</strong>：</p>
 
<ul>
	<li>如果多次调用这个函数，你将如何优化你的算法？</li>
</ul>
 
 
 
---
 
[提交记录](https://leetcode.cn/problems/number-of-1-bits/submissions/) | [题解](https://leetcode.cn/problems/number-of-1-bits/solution/)

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