LeetCode - Number of 1 Bits

Number of 1 Bits

2015.4.17 05:48

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.

Solution:

　　Old problem.

Accepted code:

// 1AC, water
class Solution {
public:
    int hammingWeight(uint32_t n) {
        int ans = 0;
        
        while (n) {
            n = n & (n - 1);
            ++ans;
        }
        
        return ans;
    }
};