326. Power of Three (Easy)

https://leetcode.com/problems/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

Follow up:
Could you do it without using any loop / recursion?

Solutions

1.

class Solution {

    // Solution without loop or recursion.

    public boolean isPowerOfThree(int n) {
        return n > 0 && 1162261467 % n == 0;
    }
}

2.

class Solution {

    // Strictly speaking, problem requires solution without loop or recursion and following is not legitimate.

    public boolean isPowerOfThree(int n) {
        if (n < 1) {
            return false;
        }

        while (n % 3 == 0) {
            n /= 3;
        }

        return n == 1;
    }
}

Incorrect Solutions

References

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