// x&(x-1) 清零最低位的 1
    public int HammingWeight(unint n)
    {
        int num = 0;

        while (num != 0)
        {
            n &= (n - 1);
            num++;
        }
        return(num);
    }
    public uint reverseBits(unint n)
    {
        uint res   = 0;
        int  power = 31;

        while (n != 0)
        {
            res += (n & 1) << power;
            n    = n >> 1;
            power--;
        }
        return(res);
    }