342. Power of Four

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

Python

Straight forward solution

class Solution:
    def isPowerOfFour(self, n: int) -> bool:
        for i in range(16):
            if n == 4**i:
                return True
        return False

Math

from math import log2


class Solution:
    def isPowerOfFour(self, n: int) -> bool:
        if n <= 0:
            return False
        return log2(n) % 2 == 0

Bit Manipulation

class Solution:
    def isPowerOfFour(self, n: int) -> bool:
        if n <= 0:
            return False

        if n & (n-1) != 0:
            return False

        # 2^32
        return n & 0b10101010101010101010101010101010 == 0