342. Power of Four

Given an integer n, return true if it is a power of four. Otherwise, return false.

An integer n is a power of four, if there exists an integer x such that n == 4x.

 

Example 1:

Input: n = 16
Output: true

Example 2:

Input: n = 5
Output: false

Example 3:

Input: n = 1
Output: true

 

Constraints:

• -231 <= n <= 231 - 1

---

class Solution:
    def isPowerOfFour(self, n: int) -> bool:
        target=1
        while target<=n:
            if target==n:
                return True
            else:
                target*=4
        return False