Meta·Software Engineer·Technical Phone Screen
Apr 2026
Meta coding round, and they took the classic grid BFS problem and added a whole layer of keys and locked doors on top of it. Not the hardest thing in the world if you've seen it before, but I hadn't really drilled the bitmask state extension and it showed.
- Given a grid where some cells are locked doors and others contain keys, find the shortest path from start to goal. Collecting a key permanently unlocks all doors of that color. How do you solve this efficiently?
“I started with plain BFS and the interviewer immediately asked what happens when the same cell is visited twice but with different keys collected.” The rest of the author's notes on Software 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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