Number of 1 Bits

Description

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.

Hint

Train of Thought

O(n) to O(1)

Code

public class Solution {

        public int hammingWeight(int n) {
            int count = 0;

            while(n != 0){
                n = n & (n - 1);
                count++;
            }

            return count;
        }
    }

Complexity