【LeetCode】191. 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.

 

思路：n&(n-1)消除一个最低位的1

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