Problem
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
Example 2:
Input: n = 0
Output: false
Example 3:
Input: n = 9
Output: true
Constraints:
-2^31 <= n <= 2^31 - 1
Follow up: Could you solve it without loops/recursion?
Solution
/**
* @param {number} n
* @return {boolean}
*/
var isPowerOfThree = function(n) {
let a = Math.log(n) / Math.log(3)
return Math.abs(a - Math.round(a)) < 1e-10
};
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(n).