342. Power of Four

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

Example 1:

Input: 16 Output: true Example 2:

Input: 5 Output: false Follow up: Could you solve it without loops/recursion?

思路：跟上题一样，4**18%num求余，为0 再加一条，num%3求余不为2

代码：python3

class Solution:
    def isPowerOfFour(self, num: int) -> bool:
        return num>0 and 4**18%num==0 and num%3!=2