Verkada phone screen - motion detection intervals + heartbeat SD, Rejected
Replies (5)
Thanks for sharing. The multi-camera overlap variant is actually the hard part. Did you have to find windows where all N cameras exceed threshold at the same time, or just any 2?
All N cameras simultaneously. So you merge each camera's threshold intervals separately first, then intersect across all cameras. I had the right idea but my intersection logic had an off-by-one I couldn't fix in time.
The heartbeat design with Redis sorted set is a solid approach. Did they ask about what happens when a device sends a delayed ping vs. just going silent?
They didn't go there. The interviewer kind of steered away from edge cases and kept it high level. Felt like they just wanted to see if I'd reach for something reasonable before the time ran out.
Had my Verkada phone screen a few months back. Same motion detection question, same extension to multi-camera. I think it's pretty standard for them at this point. Didn't make it past either tbh.
Good writeup. Saved for when I eventually get to them. The LC 56 variant in camera domain is clever — obvious in hindsight but would throw me off in an interview if I wasn't expecting it.
Did the recruiter say anything about timeline before the rejection? I got a phone screen scheduled and haven't heard back in 10 days.