Write a function that takes an unsigned integer and returns the number of ’1‘ bits it has (also known as the Hamming weight).

For example, the 32-bit integer ’11‘ has binary representation 00000000000000000000000000001011, so the function should return 3.

题目标签：Bit Manipulation

　　这题给我们一个integer，让我们找到bits中1的个数，利用 & 1 判断bit是不是1，然后利用 >> 来移动bits。

Java Solution:

Runtime beats 16.07% 

完成日期：06/26/2017

关键词：Bit Manipulation

关键点：用 & 拿到bit， 用 >> 来移动bits

 1 public class Solution 
 2 {
 3     // you need to treat n as an unsigned value
 4     public int hammingWeight(int n) 
 5     {
 6         int res = 0;
 7         
 8         for(int i=0; i<32; i++)
 9         {
10             if((n & 1) == 1) // meaning the most right bit is 1
11                 res++;
12             
13             n = n >> 1; // shift to right 1 bit
14         }
15         
16         return res;
17     }
18 }

参考资料： N/A

LeetCode 191. Number of 1 bits （位1的数量）