326. Power of Three

题目：

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?

链接：

https://leetcode.com/problems/power-of-three/?tab=Description

3/7/2017

不满足题目的解法，注意n == 1也是true

public class Solution {
    public boolean isPowerOfThree(int n) {
        if (n == 1) return true;
        if (n == 2) return false;
        while (n > 3 && n % 3 == 0) n /= 3;
        if (n == 3) return true;
        return false;
    }
}

可以简化为

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

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

        return n == 1;
    }
}

题目给出的4种解法，然而并不觉得比native解法好到哪里去。

https://leetcode.com/articles/power-of-three/