230918 Power of 2

【题意】：判断一个数字是否 2 的阶乘

【Excepted】：

• Time Complexity:O(log N).
• Auxiliary Space:O(1).

Solution

class Solution:
    def isPowerofTwo(self,n):
        while n > 1 and n % 2 == 0:
            n //= 2
        return n == 1

class Solution:
    def isPowerofTwo(self,n):
        return bin(n)[2:].count('1') == 1