binary-number-with-alternating-bits.py

# Time:  O(1)
# Space: O(1)

# 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.
    
class Solution(object):
    def hasAlternatingBits(self, n):
        """
        :type n: int
        :rtype: bool
        """
        n, curr = divmod(n, 2)
        while n > 0:
            if curr == n % 2: return False
            n, curr = divmod(n, 2)
        return True