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 = 0;
        while(n)
        {
            count++;
            n = n & (n - 1);
        }
        return count;
    }
};