LeetCode 342 Power of Four

Posted 2020-08-05

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?

 

思路：

可以沿用求3的幂次中的思路，验证log₄N是否为整数来判断。

 

解法：

 1 public class Solution
 2 {
 3     public boolean isPowerOfFour(int num)
 4     {
 5         double n = Math.log10(num) / Math.log10(4);
 6 
 7         if(n == (int)n)
 8             return true;
 9         else
10             return false;
11     }
12 }