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;
    }
}