Binary Number with Alternating Bits — LeetCode 693 Python Solution

The problem

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

Example

Input

n = 5

Output

true

Explanation

The binary representation of 5 is: 101

Python solution

class Solution:
    def hasAlternatingBits(self, n: int) -> bool:
        prev = -1
        while n:
            curr = n & 1
            if prev == curr:
                return False
            prev = curr
            n >>= 1
        return True

Complexity

Pattern: Bit Manipulation

Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 693. Binary Number with Alternating Bits is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Bit Manipulation.

The bit manipulation guide has the Python template for the pattern and the 194 LeetCode problems that use it.

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