Determine if integer is a power of two

Time: O(1); Space: O(1); easy

Given an integer, write a function to determine if it is a power of two.

class Solution1(object):
    def isPowerOfTwo(self, n) -> bool:
        """
        :type n: int
        :rtype: bool
        """
        return n > 0 and (n & (n - 1)) == 0

s = Solution1()
assert s.isPowerOfTwo(16) == True
assert s.isPowerOfTwo(24) == False

class Solution2(object):
    def isPowerOfTwo(self, n) -> bool:
        """
        :type n: int
        :rtype: bool
        """
        # print(~-n)   # 15, 23
        return n > 0 and (n & ~-n) == 0

s = Solution2()
assert s.isPowerOfTwo(16) == True
assert s.isPowerOfTwo(24) == False

See also:

https://leetcode.com/problems/power-of-two

https://www.lintcode.com/problem/power-of-two