number-of-1-bits

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Algorithms

Given a positive integer <code>n</code>, write a function that returns the number of set bits in its binary representation (also known as the <a href="http://en.wikipedia.org/wiki/Hamming_weight" target="_blank">Hamming weight</a>).

&nbsp;
Example 1:

<div class="example-block">
Input: n = 11

Output: 3

Explanation:

The input binary string 1011 has a total of three set bits.
</div>

Example 2:

<div class="example-block">
Input: n = 128

Output: 1

Explanation:

The input binary string 10000000 has a total of one set bit.
</div>

Example 3:

<div class="example-block">
Input: n = 2147483645

Output: 30

Explanation:

The input binary string 1111111111111111111111111111101 has a total of thirty set bits.
</div>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= n &lt;= 231 - 1</code></li>
</ul>

&nbsp;
Follow up: If this function is called many times, how would you optimize it?

hammingWeight

Number of 1 Bits

Reverse Bits

reverse-bits

颠倒二进制位

Power of Two

power-of-two

2 的幂

Counting Bits

counting-bits

比特位计数

Binary Watch

binary-watch

二进制手表

Hamming Distance

hamming-distance

汉明距离

Binary Number with Alternating Bits

binary-number-with-alternating-bits

交替位二进制数

Prime Number of Set Bits in Binary Representation

prime-number-of-set-bits-in-binary-representation

二进制表示中质数个计算置位

Convert Date to Binary

convert-date-to-binary

将日期转换为二进制表示

Bit Manipulation

Divide and Conquer

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 设置位 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>）。

&nbsp;

示例 1：

<pre>
输入：n = 11
输出：3
解释：输入的二进制串 <code>1011&nbsp;中，共有 3 个设置位。</code>
</pre>

示例 2：

<pre>
输入：n = 128
输出：1
解释：输入的二进制串 10000000&nbsp;中，共有 1 个设置位。
</pre>

示例 3：

<pre>
输入：n = 2147483645
输出：30
解释：输入的二进制串 1111111111111111111111111111101 中，共有 30 个设置位。</pre>

&nbsp;

提示：

<ul>
	<li><code>1 &lt;= n &lt;= 231 - 1</code></li>
</ul>

<ul>
</ul>

&nbsp;

进阶：

<ul>
	<li>如果多次调用这个函数，你将如何优化你的算法？</li>
</ul>