First call: A Software Engineer Manager reached out over LinkedIn and asked about my background and experiences during a call. This was essentially a lighter version of a hiring manager interview, which usually occurs at later stages of the interview process. I found it to be a refreshing change from the typical recruiter routine of asking basic questions about myself, as we were able to delve deeper into my experiences, and the interviewer had a technical background to understand them.

Phone technical interview (coding on HackerRank CodePair):

• No introductions, straight into coding.
• The question was intended to be multi-part, but all parts were presented at once, which influenced how I approached it.
• The top priority was to produce compilable, running code using HackerRank CodePair's feature. Some of my thoughts on this:
  • The interviewer did not seem engaged; it felt like a situation where no one was present, and I was meant to complete a one-hour LeetCode/HackerRank coding challenge.
  • The interviewer was not interested in design approaches or time/space complexities.
  • A significant amount of time was spent on making the code compile and run (I was using Java), fixing brackets, method calls, missing libraries, etc. I felt this was not a good use of interview time. Ultimately, my code did not run, which I believe was the reason for my rejection.
  • A tricky aspect of using Java is instantiating an inner class within a static main method (a solution can be found on Stack Overflow). While I'm not familiar with Python, I imagine it would be simpler to produce running code in Python, giving an advantage to interviewers who know Python.
  • It's true that working code is required in a professional environment. However, it wouldn't be under such a strict time limit. I would also have time for design, implementation, writing tests, alarms/monitors, etc. Furthermore, I would use advanced IDEs instead of HackerRank's CodePair, which is far inferior.

One other issue was that I had to reschedule the phone interview because the meeting invite did not clearly state that we would be using HackerRank CodePair's video call feature instead of the Google Meet link provided. This resulted in me missing my first interview. It would be beneficial to clarify this in the meeting invite and to use Google Meet for video chat, as it offers a larger screen for better visibility of the interviewer.

Implement a key-value datastore that supports querying for historic values. For every key, there can be multiple values at different timestamps. It should support querying by a key only, or by a key and timestamp.