342. 4的幂(javascript)342. Power of Four
给定一个整数,写一个函数来判断它是否是 3 的幂次方。如果是,返回 true ;否则,返回 false 。
整数 n 是 3 的幂次方需满足:存在整数 x 使得 n == 3^x
Given an integer n, return true if it is a power of three. Otherwise, return false.
An integer n is a power of three, if there exists an integer x such that n == 3^x.
示例 1:
输入:n = 27
输出:true
示例 2:
输入:n = 0
输出:false
示例 3:
输入:n = 9
输出:true
示例 4:
输入:n = 45
输出:false
提示:
- -231 <= n <= 231 - 1
var isPowerOfThree = function(n) {//0是特殊情况if(n===0)return falsewhile(n%3===0){n/=3}return n==1
};
var isPowerOfThree = function(n) {while(n!=0&&n%3===0){n/=3}return n==1
};
leetcode:https://leetcode-cn.com/problems/power-of-three/