191. 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.

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