# Question

Formatted question description: https://leetcode.ca/all/326.html

 326	Power of Three

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

Could you do it without using any loop / recursion?



# Algorithm

The most straightforward way is to keep dividing by 3 to see if the final iterative quotient is 1. Pay attention to the case where the input is negative and 0.

If no loop, there is a tricky method. Since the input is an int, the range of positive numbers is 0 - 2^31, and the largest power of 3 allowed in this range is 3^19=1162261467, so we only need to see if this number is divisible by n.

Java