LeetCode | 342. Power of Four

题目

Given an integer n, return true if it is a power of four. Otherwise, return false.
An integer n is a power of four, if there exists an integer x such that n == 4^x.

Example 1:

Input: n = 16
Output: true

Example 2:

Input: n = 5
Output: false

Example 3:

Input: n = 1
Output: true

Constraints:

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

代码

class Solution {
public:
    bool isPowerOfFour(int num) {
        int base = log(num*1.0) / log(4.0);
        if(pow(4, double(base)) == num && num)
            return true;
        else
            return false;
    }
};

一道简单题~ 但效率排名不是太高呀~