Number of 1 Bits

题目：

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.

unsigned integer： http://baike.baidu.com/view/6052699.htm

 1 public class Solution {
 2     // you need to treat n as an unsigned value
 3     public int hammingWeight(int n) {
 4     
 5         int res=0;
 6         int k=0;
 7         for(int i=1;i<=32;i++)
 8         {
 9             res=n&1;
10             if(res==1) k++;
11             n=n>>1;        
12             
13         }
14         return k;
15     }
16 }