342. Power of Four

难度: Easy

题目描述

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 == 4x.

 

Example 1:

Input: n = 16
Output: true

Example 2:

Input: n = 5
Output: false

Example 3:

Input: n = 1
Output: true

 

Constraints:

• -231 <= n <= 231 - 1

 

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

解题思路

代码实现

解决方案

java

public class Solution {
    public boolean isPowerOfFour(int num) {
        
        if (num == 4 || num ==1) {
        return true;
        }
        int yushu = num % 4;
        int chushu = num/4;

        while(chushu>=4&&yushu==0){
            if (chushu == 4) {
                return true;
            }
             num = chushu;
             yushu = num % 4;
             chushu = num/4;
        }
        return false;

        
        
        
        
    }
}