342. Power of Four

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# 題目敘述

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 == 4^x .

# Example 1

Input: n = 16
Output: true

# Example 2

Input: n = 5
Output: false

# Example 3

Input: n = 1
Output: true

# 解題思路

# Solution

class Solution {

    public boolean isPowerOfFour(int n) {

        while (n % 4 == 0 && n > 0) {

            n /= 4;

        }

        return n == 1;

    }

}