191. 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.

public class Solution {
// you need to treat n as an unsigned value
public int hammingWeight(int n) {
int re = 0;

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

return re;

}

}