题目

Given an integer n, return true if it is a power of three. Otherwise, return false.

An integer n is a power of three, if there exists an integer x such that n == 3x.

Example 1:

Input: n = 27
Output: true

Example 2:

Input: n = 0
Output: false

Example 3:

Input: n = 9
Output: true

Example 4:

Input: n = 45
Output: false

Constraints:

-2^31 <= n <= 2^31 - 1

Follow up: Could you solve it without loops/recursion?

代码

class Solution {
public:
    bool isPowerOfThree(int n) {
        int base = log10(n*1.0) / log10(3.0);
        if(pow(3, double(base)) == n && n)
            return true;
        else
            return false;
    }
};

附加问题正好是：可以不用循环和递归实现吗？
然而我的实现貌似是最粗暴简单的解法，效率超出了排行榜233333