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