326. Power of Three

• Difficulty: Easy

• Topics: Math

• Similar Questions:

  • Power of Two

  • Power of Four

Problem:

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?

Solutions:

class Solution {
public:
    bool isPowerOfThree(int n) {
        if (n <= 0) return false;

        int largest = 3;
        while (largest <= INT_MAX/3) {
            largest *= 3;
        }

        return largest % n == 0;
    }
};