## 1. 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.

## 2. Solution

I just make list that contains all 2 ^ n of problem constraints. After that, i confirm n is in list.

```
class Solution:
def isPowerOfTwo(self, n: int) -> bool:
sub_list = [2 ** i for i in range(-31, 32)]
return n in sub_list
```