326. Power of Three
Description
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 == 3x.
Example 1:
Input: n = 27 Output: true Explanation: 27 = 33
Example 2:
Input: n = 0 Output: false Explanation: There is no x where 3x = 0.
Example 3:
Input: n = -1 Output: false Explanation: There is no x where 3x = (-1).
Constraints:
-231 <= n <= 231 - 1
Follow up: Could you solve it without loops/recursion?
Solutions
Solution: Recursion
- Time complexity: O(1)
- Space complexity: O(1)
JavaScript
js
/**
* @param {number} n
* @return {boolean}
*/
const isPowerOfThree = function (n) {
if (n === 1) return true;
if (n <= 0) return false;
const num = n / 3;
if (num % 1 !== 0) return false;
return isPowerOfThree(num);
};