Engineering Manager (L6) Interview Experience

The prompt was ambiguous, so I first defined requirements, UX expectations, and rough user scale in the millions. My first instinct was to use graph-specific storage and let it calculate relationships, but they pushed me to own the implementation. I said I would pre-calculate graph relationships in memory for speed, then acknowledged full precomputation would not stay manageable at that size. My fallback was to store second-degree connections in a hash-based list and treat anything outside that set as third-degree for instant lookup.

I sketched the usual producer, processing layer, and consumer flow, then clarified that the target was near real time, under a minute. I initially reached for a dedicated streaming system and treated it like a black box, but the interviewer wanted the lower-level design. In the room I did not land that part well enough. Afterward I realized I should have described distributed ETL-style processing with separated storage so consumers could query and retry cleanly instead of stopping at the framework name.

I first clarified that there are different cases, especially someone who used to be a high performer and then dropped off versus someone consistently struggling. I answered from that lens and walked through how I would diagnose the reason, set expectations, and respond based on the situation rather than treating every low performer the same way. He was fine with that clarification and let me structure the answer that way.

I answered from my management principles instead of treating performance as a free pass. I said I would address the behavior directly, make the team impact visible, and push for a workable path where they can keep contributing without damaging the rest of the group. The question was hypothetical, so I kept it practical and principle-based.

I said I would start by understanding why morale dropped, then rebuild trust and clarity before trying to drive big changes. I talked about setting up the team in a stable way, getting people aligned again, and making sure high performers stay engaged without creating two classes of engineers. This one was also hypothetical, but it was a pretty standard EM scenario.

Review this code, identify the problems, fix it, and walk through test cases so it correctly finds the lowest missing integer from a stream of inputs.

The underlying problem itself was simple if I wrote it fresh, probably a hash-table style solution, but their code used interval or sequence logic and was over 200 lines in a Google Doc. I spent the first 20 to 25 minutes just understanding what it was trying to do and why it was broken. There were some obvious syntax and convention issues, but the real challenge was the logic. By the time I had a path to fix it and reason through manual test cases, I was basically out of time. That was my biggest mistake.