Problem of The Day: Power of Three

Problem Statement

leetcode problem link

Brute Force [Accepted]

class Solution:
    def isPowerOfThree(self, n: int) -> bool:
        if n == 1:
            return True
        if 0 <= n < 1:
            return False
        return self.isPowerOfThree(n / 3)

Other Approach [Accepted]

import math
class Solution:
    def isPowerOfThree(self, n: int) -> bool:
        if n <= 0:
            return False
        val = math.log10(n) / math.log10(3)
        str_val = str(val)
        res = str_val.split('.')[1]
        return '0' == res

Editorial

Approach 1: Loop Iteration

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

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

        return n == 1;
    }
}

Approach 2: Base Conversion

public class Solution {
    public boolean isPowerOfThree(int n) {
        return Integer.toString(n, 3).matches("^10*$");
    }
}

Approach 3: Mathematics

public class Solution {
    public boolean isPowerOfThree(int n) {
        return (Math.log(n) / Math.log(3) + epsilon) % 1 <= 2 * epsilon;
    }
}

Approach 4: Integer Limitations

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