[LeetCode] 342. Power of Four

 Problem : https://leetcode.com/problems/power-of-four/

A recursive solution :

class Solution:
    def isPowerOfFour(self, num: int) -> bool:
        if num == 0: return False
        return num == 1 or num % 4 == 0 and self.isPowerOfFour(num // 4)

A math solution:

If N is power of 4, Log(N, base=4) is an integer.

class Solution:
    def isPowerOfFour(self, num: int) -> bool:
        return num > 0 and log(num, 4) % 1 == 0