LeetCode *** 342. Power of Four

题目：

Given an integer (signed 32 bits), write a function to check whether it is a power of 4.

Example:
Given num = 16, return true. Given num = 5, return false.

Follow up: Could you solve it without loops/recursion?

分析：

。

代码：

class Solution {public:    bool isPowerOfFour(int num) {                return num>0&&!(num&(num-1))&&!((num-1)%3);            }};