1.描述

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?

2.分析

3.代码

class Solution {
public:
    bool isPowerOfFour(int num) {
        if (num <= 0) return false;
        if (num == 1) return true;
        return num % 4 == 0 ? isPowerOfFour(num / 4) : false;
    }
};