## Question

Write a function that takes the binary representation of an unsigned integer and returns the number of '1' bits it has (also known as the Hamming weight).

## Algorithm

A similar question to the question 338. Counting bits. Use n&n-1 to count the non zero bit from least significant bit.

## Code

public class Solution { // you need to treat n as an unsigned value public int hammingWeight(int n) { int res = 0; while (n != 0) { res++; n &= n-1; } return res; } }