Binary number with alternating bits

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

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 Solution1(object):
    def hasAlternatingBits(self, n) -> bool:
        """
        :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

s = Solution1()
assert s.hasAlternatingBits(5) == True
assert s.hasAlternatingBits(7) == False
assert s.hasAlternatingBits(11) == False
assert s.hasAlternatingBits(10) == True

See also:

https://leetcode.com/problems/binary-number-with-alternating-bits

https://www.lintcode.com/problem/binary-number-with-alternating-bits