Meta·Performance Engineer·Technical Phone Screen
Apr 2026
Meta Production Engineer loop, and this one was almost entirely a single algorithmic problem about pairing dinosaur crossings across two sensor lines and computing speeds. PE-track specific apparently, so don't expect to see this if you're not in that loop. The follow-ups got progressively more annoying.
- You have two sensor lines a fixed distance apart. Each line records timestamps when a dinosaur crosses it. Pair up crossings from line 1 and line 2 that represent the same dinosaur (within a reasonable time window), then compute the speed for each pair. Follow-ups include filtering by a speed threshold and handling multiple dinosaurs in flight simultaneously.
“My first instinct was brute force, match every line-1 timestamp against every line-2 timestamp and pick the closest.” The rest of the author's notes on Performance Engineer interview at Meta, Technical Phone Screen round, covers how they worked through the question, what the panel pushed back on, and what they would do differently.
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