'''
231. Power of Two

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

Example 1:

Input: 1
Output: true 
Explanation: 20 = 1
Example 2:

Input: 16
Output: true
Explanation: 24 = 16
Example 3:

Input: 218
Output: false
'''

#Solution-1

class Solution(object):
    def isPowerOfTwo(self, n):
        """
        :type n: int
        :rtype: bool
        """
        i = 0
        while True:
            i_power = 2 ** i
            if i_power == n:
                return True
            else:
                if i_power > n:
                    return False
                i+=1
            

#Solution-2


class Solution(object):
    def isPowerOfTwo(self, n):
        """
        :type n: int
        :rtype: bool
        """
        if n <= 0:
            return False
        else:
            return (n & (n-1)) == 0
            