Leetcode 326. Power of Three

Given an integer, write a function to determine if it is a power of three.
Follow up:
Could you do it without using any loop / recursion?
Credits:
Special thanks to @dietpepsi for adding this problem and creating all test cases.
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public class Solution {    public boolean isPowerOfThree(int n) {        if(n == 0) {            return false;        }        if(n == 1) {            return true;        }        while(n % 3 == 0) {            n /= 3;        }        if(n == 1) {            return true;        }        else {            return false;        }    }}

只写出了用迭代的方法，Google了一下，找到了python版本的写法，要用到Math.log()。但是无奈，Java的标准库中并没有以3为底的log函数。