342. Power of Four(easy)

Easy

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

Example 1:

Input: 16

Output: true

Example 2:

Input: 5

Output: false

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

 

C++:

/* * @Autor: SourDumplings * @Date: 2019-09-11 08:10:46 * @Link: https://github.com/SourDumplings/ * @Email: changzheng300@foxmail.com * @Description: https://leetcode.com/problems/power-of-four/ */ class Solution { public: bool isPowerOfFour(int num) { double d = log(num) / log(4); return fabs(d - (int)d) < 1e-5; } };

 Java:

/* * @Autor: SourDumplings * @Date: 2019-09-11 08:15:35 * @Link: https://github.com/SourDumplings/ * @Email: changzheng300@foxmail.com * @Description: https://leetcode.com/problems/power-of-four/ */ class Solution { public boolean isPowerOfFour(int num) { return (Math.log(num) / Math.log(4)) % 1 == 0; } }