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Meta·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Meta SWE interview with a classic maze problem, apparently well-known enough that most of the sub-questions were circulating on 1point3acres beforehand. Five parts total, so if you've done your prep on that forum you'll recognize most of it.

Questions Asked (1)

Q1

Solve a maze traversal problem, broken into five progressive sub-questions.

Algorithms & Data Structures
Author's notes

The first four parts are basically public knowledge at this point if you've been lurking the usual prep forums.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem constraints and assumptions for each sub-question, then choose the appropriate algorithm (BFS for shortest path, DFS for any path) and discuss trade-offs. Progressively build from basic traversal to optimized solutions, explaining time/space complexity and edge cases at each step.

Pro tip: Demonstrate strong communication by thinking aloud and proactively discussing trade-offs between BFS and DFS, and mention how you would handle large mazes or dynamic obstacles. This shows you consider real-world scalability and not just correctness.

1. Clarify the problem

Ask about maze representation (grid, graph), start/end points, movement rules (4-directional vs 8-directional), and whether the maze is static or dynamic. Confirm if the goal is to find any path or the shortest path.

2. Choose the right algorithm

For shortest path, use BFS; for any path or memory-constrained scenarios, consider DFS. Explain why BFS guarantees shortest path in unweighted grids and discuss trade-offs.

3. Handle edge cases and constraints

Discuss handling of no path, start equals end, large mazes, and obstacles. Mention techniques like bidirectional BFS or A* for optimization if needed.

4. Analyze complexity and optimize

State time and space complexity (O(R*C) for BFS/DFS). For sub-questions, adapt to constraints like multiple queries or dynamic changes, suggesting precomputation or incremental updates.

5. Test and validate

Walk through a small example to verify the algorithm, and discuss how to test edge cases. Mention potential pitfalls like infinite loops in DFS without visited tracking.

Key Points to Mention

  • BFS vs DFS trade-offs: BFS for shortest path, DFS for memory efficiency
  • Time and space complexity: O(R*C) for grid traversal
  • Handling edge cases: no path, start=end, large grids
  • Optimization techniques: bidirectional BFS, A* with heuristics
  • Data structures: queue for BFS, stack/recursion for DFS, visited set
  • Real-world considerations: dynamic obstacles, multiple queries, memory limits

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.