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?

这题要能面试到，我吃屎。。

class Solution {
    public boolean isPowerOfThree(int n) {
        if(n ==1) return true;
        while(n%3 == 0 && n>3){
            n = n/3;
        }
        if(n ==3){
            return true;
        }
        else{
            return false;
        }
    }
}