[LeetCode]Number of 1 Bits

Number of 1 Bits

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.

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

有个简单的规律， Wegner (1960)发现的。利用x和x-1之间的关系。

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