Power of Three

LeetCode 326 | Difficulty: Easy

Easy

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

An integer n is a power of three, if there exists an integer x such that n == 3^x.

Example 1:

Input: n = 27
Output: true
Explanation: 27 = 3^3

Example 2:

Input: n = 0
Output: false
Explanation: There is no x where 3^x = 0.

Example 3:

Input: n = -1
Output: false
Explanation: There is no x where 3^x = (-1).

Constraints:

- `-2^31 <= n <= 2^31 - 1`

Follow up: Could you solve it without loops/recursion?

Topics: Math, Recursion

Look for mathematical patterns or formulas. Consider: modular arithmetic, GCD/LCM, prime factorization, combinatorics, or geometric properties.

When to use

Problems with clear mathematical structure, counting, number properties.

Solution
public class Solution {
    public bool IsPowerOfThree(int n) {
        if(n>1)
        while(n%3==0) n /= 3;
    return n==1;
    }
}

Approach	Time	Space
Solution	$O(n)$	$O(1) to O(n)$

Key Points