Robinhood full loop writeup, coding through project deep dive

Robinhood full loop writeup, coding through project deep dive

Just got the offer from Robinhood after a 4 round loop, figured I'd write up what I got since a lot of the questions here are already documented and it might save someone some prep time.

Phone screen was the dependency graph problem, basically build a graph of nodes and calculate a load factor for each one by walking the DFS chain underneath it. CoderPad with hidden tests, six or seven of them. Nothing about the problem itself was new to me, pretty sure I'd seen it mentioned around here before, but the platform trips people up if you haven't used it before. You can't rename methods once the stub is generated so plan your variable names ahead of time.

Onsite had four rounds. First was coding, got the referral leaderboard problem where person A refers B and B refers C and credits roll up the chain like a pyramid scheme. Naive solution is DFS from every node which is fine for correctness but the interviewer wanted to talk through getting it down from N squared, ended up doing a single pass with a running sum per branch instead.

Second round was system design, Job Scheduler again. Feels like it's their go-to, I'd seen a couple other posts mention it too. State machine with pending, running, failed, complete states. They care a lot more about how you handle a node crashing mid job and retry logic than about scaling numbers, so I spent most of the time on failure modes instead of throughput.

Third was project deep dive with a PPT I put together the night before. This one ran almost 50 minutes and the interviewer kept circling back to ask why I made specific technical choices, felt like the real behavioral round in disguise tbh since there wasn't a separate BQ slot anywhere in the loop.

Last was another quick technical chat, pretty low key compared to the deep dive.

Heard back in about four days and got matched to a team the following week. If anyone has Robinhood coming up, know the state machine pattern cold and actually prep a real project story for the deep dive, that round matters more than people give it credit for.