The problem required merging k sorted linked lists into a single sorted list. I began by clarifying the input format and edge cases, such as what to do if one of the lists was null. My initial thought was to use a priority queue to efficiently merge lists, which seemed like a solid approach. I also sketched out a plan to handle the merging step-by-step, mentioning how I'd keep track of the minimum node and build the resulting list iteratively.

As I implemented the solution, I encountered a minor hiccup with the implementation details. My logic was sound, but I stumbled a bit with the edge cases, particularly when a list was completely empty. The interviewer patiently guided me through these issues, helping me see how I could incorporate checks more gracefully. Their encouragement gave me the confidence to correct my approach and keep moving.

After getting the merging logic to work, I discussed the time complexity, noting that using a priority queue would yield O(N log k), where N is the total number of nodes across all lists and k is the number of lists. The interviewer seemed satisfied with this explanation and asked follow-up questions about potential optimizations. I proposed an alternate merging method using a divide-and-conquer approach, but I couldn't quite articulate it as clearly as I had hoped, which led to some back-and-forth that felt a bit disorganized.

I noticed the interviewer was making notes, which made me curious about how I was being evaluated. Despite some bumps, there were moments where I felt the flow of the discussion was strong, particularly when I was able to explain why the priority queue was efficient. We also discussed real-world scenarios; that felt encouraging and relevant as it connected the problem to practical applications.

Overall, it was a memorable experience. The challenge pushed me to think on my feet, and while I struggled with details, I felt I showcased my ability to reason through problems. The interviewer’s constructive feedback was helpful; I appreciated how they framed the questions to nudge my thinking in new directions. I left the interview with some uncertainty, particularly about my execution, but I felt I had shown my thought process and ability to adapt.

As for the outcome, I received a rejection a week later. I was initially disappointed, especially given how much I had prepared. But reflecting on the experience, I recognized that the process of grappling with the problem was valuable in itself, helping solidify my understanding of linked lists and their complexities. Every interview is a learning opportunity, and this one was no exception.