leetcode 191. Number of 1 Bits

題目描述：
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.

解題思路：
經典的求解問題，直接上代碼：

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

leetcode上題解