191 Number of 1 Bits

来源：Leetcode

原帖：https://leetcode.com/problems/number-of-1-bits/

题目：
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.

代码：

 class Solution {  
 public:  
   int hammingWeight(uint32_t n) {  
     int count = 0;  
     while (n) {  
       n = (n & (n-1));  
       count++;  
     }  
     return count;  
   }  
 };