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.

题目大意：给一个无符号数，返回这个数二进制表示中1的数量。

解题思路：按位和0x1与操作，计算即可。

    public int hammingWeight(int n) {

        int res = 0;

        while(n!=0){

            if((n&0x1)==1){

                res++;

            }

            n=n>>>1;

        }

        return res;

    }