I rarely post here, but I felt compelled to share my experience interviewing with this company, as everything that transpired after the phone screen was shockingly weird and terrible.

I made it to the phone screen, and I absolutely loved that part of the process. The task was to use my own coding environment to solve a simple, industry-appropriate problem. I truly appreciated their interviewing style and believe all companies should adopt their standard of evaluation, which is based on practical, industry-like questions handled within the interviewee's own programming environment. I also had a great conversation with my interviewer. At the end, my interviewer even told me I did great. This wasn't just implied; they said it word-for-word. Honestly, I thought so too, and I'd go as far as to say it was the most enjoyable and best-performing interview I've ever had.

A week later, however, I received a rejection. I completely understand that how you perceive your performance often has no correlation with the actual outcome. However, usually, you have some intuition that can be somewhat reliable, based on your performance and the rapport you establish. I answered all questions correctly, conducted extremely thorough testing, and was even told by my interviewer that I did great. The interview itself also seemed to extend beyond its scheduled time because we had such an engaging discussion about my questions for the company.

If I had received feedback explaining the reason for this rejection—whether it was a headcount issue or perhaps the interviewer being untruthful about candidates' performance—I wouldn't be posting this. However, the fact remains that I received absolutely no feedback. The recruiter completely ghosted me. It wasn't as if I inquired aggressively, which might have elicited a response. I asked very courteously, stating that I loved the interview process and would appreciate any feedback to improve my chances in the future. Nothing.

TL;DR: My interviewer told me, word-for-word, that I did great, then I was ghosted with no feedback.

It was a relatively simple question that a basic understanding of HashMaps and HashSets would allow you to answer quite easily.