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

My initial code:

 1 class Solution:
 2     # @param {integer} n
 3     # @return {boolean}
 4     def isPowerOfTwo(self, n):
 5         if n==0 :
 6             return False
 7         if n==1 or n==2:
 8             return True
 9         if n % 2 != 0:
10             return False
11         if n < 4 and n 
12         return self.isPowerOfTwo(n/2)

After google the internet, the best solution is:

class Solution:
    # @param {integer} n
    # @return {boolean}
    def isPowerOfTwo(self, n):
        if n<= 0 or n&(n-1) != 0:
            return False
        return True