Bitwise XOR Subsequences

Problem Overview

• Find the maximum length of a subsequence where each adjacent pair has bitwise XOR equal to k; single-element subsequences are valid.
• Input: n, array arr of n integers, and integer k; Output: the length of the longest valid subsequence.
• Constraints: 1 ≤ n ≤ 1e5, 0 ≤ arr[i], k ≤ 1e6; standard line-by-line array input.
• Domain: array processing and bitwise operations; subsequence keeps order and may skip elements; a classic coding interview problem.
• This interview question is from Goldman Sachs interviews.