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Fireworks AI is a startup that provides a fast, cost-efficient inference platform for running and serving generative AI models. It is known for optimizing the deployment of open-source large language models and enabling developers to build and scale AI applications.

2 interview notes · updated Jul 2026

fireworks ai·Software Engineer·Technical Phone Screen

Jun 2026
Interviewed for a software engineer role at Fireworks AI and got a problem about maintaining a live set of merged busy intervals on a GPU. The core challenge was making insertion efficient while also supporting idle time queries. Pretty meaty for a single coding round.
  • Design a data structure that tracks busy time intervals for a GPU as tasks arrive in a stream. Each task adds a busy interval, and you need to support efficient insertion with merging of overlapping or adjacent intervals, plus a query that returns the current idle intervals. Target O(log n) insertion using a sorted structure.

“I knew the merge intervals problem but doing it online, as a stream, is a different beast.”

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fireworks ai·Software Engineer·Technical Phone Screen

May 2026
Interviewed for a software engineer role at Fireworks AI and got a scheduling/interval problem that felt more systems-adjacent than pure leetcode. Clean problem, but the trick is in the sweep logic and I almost fumbled the idle interval bookkeeping.
  • Given a list of GPU tasks each defined by a start time, end time, and node ID, find all time intervals during which no task is running on any GPU.

“The event-sweep approach clicked pretty fast: emit a +1 at each start and -1 at each end, sort everything, then walk through tracking how many tasks are active.”

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