Bny Mellon Software Engineer Interview Guide

Honestly the whole thing was three rounds and I was way more nervous for the system design one than I expected. First round was a quick chat with the hiring manager, mostly vibes, felt fine. Second round was a live coding thing and I completely blanked on a basic edge case for like two minutes, just sat there staring at the screen while the interviewer waited. Recovered eventually but my heart was going. Third round was system design and that's where I actually felt good, probably because it overlapped with stuff I'd already built at work. The surprising part was how much they cared about how I talked through tradeoffs rather than landing on the "right" answer. I left convinced I'd bombed it because of the coding round, then got the offer two days later and just sat there confused for a bit before telling anyone.

Questions asked: Okay so round two, the coding one, the actual question was something like "given a list of time intervals representing booked appointment slots, write a function that merges overlapping ones and tells you the free gaps in a day." Sounds simple written out like that but I started overengineering it with a heap when a sorted list and a single pass would've done it, that's where I lost the two minutes just staring. Interviewer eventually nudged me with "do you need that structure for this input size" and I felt my face go red over a video call, which is a special kind of humiliating. Round three, system design, they asked me to design a multi tenant scheduling system that takes booking requests from multiple channels at once and guarantees no double bookings even if two requests hit at the exact same time. I basically just talked through the same overlap and locking logic I'd built for real, which is probably why it felt comfortable instead of stressful. There was also a take home before any of this, not technical exactly, just a written prompt asking me to describe a time I disagreed with a decision and what I did about it, no word limit given which threw me more than any code question did.