Number of 1 Bits（Difficulty: Easy）

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.

实现：

 1 class Solution {
 2 public:
 3     int hammingWeight(uint32_t n) {
 4         int count = 0;
 5         while(n)
 6         {
 7             count++;
 8             n = n & (n - 1);
 9         }
10         return count;
11     }
12 };