PowerOfTwo.java

//Runtime: 1 ms, faster than 99.97% of Java online submissions for Power of Two.
//Memory Usage: 35.8 MB, less than 76.17% of Java online submissions for Power of Two.

/**
  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
Example 4:

Input: n = 4
Output: true
Example 5:

Input: n = 5
Output: false
 

Constraints:

-231 <= n <= 231 - 1
 

Follow up: Could you solve it without loops/recursion?
*/

class Solution {
    public boolean isPowerOfTwo(int n) {
        if(n == 0) return false;
        double log = Math.floor((Math.log(n) / Math.log(2)));
        return Math.pow(2, log) == n;
    }
}