Implement an in-memory database in CodeSignal, with each round adding more functionality.

"This process felt very different from most of the interviews I've done. There was no classic DS&A round at all. Instead, they tested raw coding implementation speed early on with database-style CodeSignal rounds, and then the final loop shifted hard into research thinking and a pretty fundamental understanding of LLMs. The most unusual part was the structure of the final: a 15-minute open-ended alignment brainstorm with almost no interviewer feedback, followed by a 55-minute Colab notebook exercise where I had to complete part of an LLM inference workflow. It also felt like a newer process when I did it, so I was mostly inferring what to expect from the emails rather than finding much info online."