Problem
Given an integer n, return true if it is a power of two. Otherwise, return false.
An integer n is a power of two, if there exists an integer x such that n == 2x.
Example 1:
Input: n = 1
Output: true
Explanation: 20 = 1
Example 2:
Input: n = 16
Output: true
Explanation: 24 = 16
Example 3:
Input: n = 3
Output: false
Constraints:
-231 <= n <= 231 - 1
Follow up: Could you solve it without loops/recursion?
Solution
/**
* @param {number} n
* @return {boolean}
*/
var isPowerOfTwo = function(n) {
if (n <= 0) return false;
if (n === 1) return true;
if (n % 2) return false;
return isPowerOfTwo(n / 2);
};
Explain:
nope.
Complexity:
- Time complexity : O(log(n)).
- Space complexity : O(1).