Leetcode: Binary Number with Alternating Bits

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Binary number

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Given a positive integer, check whether it has alternating bits: namely, if two adjacent bits will always have different values.

Example 1:
Input: 5
Output: True
Explanation:
The binary representation of 5 is: 101

Example 2:
Input: 7
Output: False
Explanation:
The binary representation of 7 is: 111.

Example 3:
Input: 11
Output: False
Explanation:
The binary representation of 11 is: 1011.

Example 4:
Input: 10
Output: True
Explanation:
The binary representation of 10 is: 1010.

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

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## https://code.dennyzhang.com/binary-number-with-alternating-bits
class Solution(object):
    def hasAlternatingBits(self, n):
        """
        :type n: int
        :rtype: bool
        """
        if n == 0 or n == 1:
            return True

        last_digit = None
        while n != 0:
            if last_digit is None:
                last_digit = n % 2
            else:
                if last_digit + (n % 2) != 1:
                    return False
                last_digit = n % 2
            n = n / 2
        return True

if __name__ == '__main__':
    s = Solution()
    print s.hasAlternatingBits(5)
    print s.hasAlternatingBits(3)
    print s.hasAlternatingBits(7)
    print s.hasAlternatingBits(11)
    print s.hasAlternatingBits(10)