191. Number of 1 Bits

1.输入是无符号整数，供32位，结合两个步骤 a.向右移1位 b.当前数与 1 按位与，得到当前数的末位数字是0还是1

public class Solution {    // you need to treat n as an unsigned value    public int hammingWeight(int n) {        int ans = 0;        for(int i = 0;i < 32;i++){            ans += n & 1;            n = n >>> 1;        }        return ans;    }}