二进制中一的个数

解法1：

public class Solution {
    public int hammingWeight(int n) {
        int res = 0;
        while(n != 0) {
            res += n & 1;
            n >>>= 1;
        }
        return res;
    }
}

解法2：

public class Solution {
    public int hammingWeight(int n) {
        int res = 0;
        while(n != 0) {
            res++;
            n &= n - 1;
        }
        return res;
    }
}

链接：https://leetcode-cn.com/problems/er-jin-zhi-zhong-1de-ge-shu-lcof/solution/mian-shi-ti-15-er-jin-zhi-zhong-1de-ge-shu-wei-yun/