This one is a blend of “merging sorted streams” + “stateful aggregation”.

What I did:
Min-heap over K feeds (timestamp as the key) so events are always chronological when you pop.
Track a running cumulative price (initial price = 0) and output absolute prices, not deltas.

discussed some edge cases and how i would handle them with the interviewer:
multiple feeds emitting at the same timestamp
negative deltas
empty feeds / single feed

There's a similar problem here I practiced so I had plenty of time:
https://offerretriever.com/questions/10

The interviewer actually arrived super late, so it was kind of a bad interview experience. He also feels super tired and stressed and didnt' really want to be there or talk to me. Luckily I've practiced this problem before, and was able to finish the problem.

Really hard to say what the interview result will be.