Number of 1 Bits

Problem

Number of 1 Bits

You are given an unsigned integer n. Return the number of 1 bits in its binary representation.

You may assume n is a non-negative integer which fits within 32-bits.

Examples

Example 1:

Input: n = 00000000000000000000000000010111

Output: 4

Example 2:

Input: n = 01111111111111111111111111111101

Output: 30

Constraints

You should aim for a solution with O(1) time and O(1) space.

Solution

Shift bits right, and increment if trailing 1.

class Solution {
public:
    int hammingWeight(uint32_t n) {
        int count = 0;
        while (n) {
            count += (n % 2) ? 1 : 0;
            n = n >> 1;
        }
        return count;
    }
};