Question

Given an integer, write a function to determine if it is a power of three.

Example 1:

Input: 27
Output: true

Example 2:

Input: 0
Output: false

Example 3:

Input: 9
Output: true

Example 4:

Input: 45
Output: false

Follow up:

Could you do it without using any loop / recursion?

Solution

class Solution(object):
    def isPowerOfThree(self, n):
        """
        :type n: int
        :rtype: bool
        """
        if n <= 0:
            return False
        elif n == 1:
            return True
        else:
            while n != 1:
                if n % 3 == 0:
                    n //= 3
                else:
                    return False
            return True