LeetCode 42. Power of Four

Given an integer (signed 32 bits), write a function to check whether it is a power of 4.

Example:
Given num = 16, return true. Given num = 5, return false.

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

Credits:
Special thanks to @yukuairoy for adding this problem and creating all test cases.

class Solution {
public:
    bool isPowerOfFour(int num) {
        return num <= 0 ? false : pow(4, (round)(log(num) / log(4))) == num;
    }
};

class Solution {

public:

bool isPowerOfFour(int num) {

return num <= 0 ? false : pow(4, (round)(log(num) / log(4))) == num;

}

};