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.

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

1.递归运算，虽然leet不通过，因为时间原因

public class Solution {// you need to treat n as an unsigned valuepublic static int hammingWeight(int n) {if(n==0) return 0;if(n==1) return 1;int total=1;int index=1;while(n-total*2>=0){total=total*2;}n=n-total;index=index+hammingWeight(n);return index;}

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

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