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：

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