题目
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:
-2^31 <= n <= 2^31 - 1
Follow up: Could you solve it without loops/recursion?
思路
列出所有2的幂，然后判断n是否在此中。
代码
python版本：
class Solution:
def isPowerOfTwo(self, n: int) -> bool:
nums = [pow(2, i) for i in range(32)]
return True if n in nums else False
