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Glean·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Glean software engineer interview with a classic game implementation problem. Pretty straightforward on the surface but the follow-up about end-game detection is where things get interesting.

Questions Asked (1)

Q1

Implement the 2048 game. Follow-up: how do you detect when the game is over?

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

The core implementation felt manageable once I mapped out the tile-shifting logic on a 4x4 grid.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the requirements and constraints (e.g., board size, input method, win condition). Then outline a clean object-oriented design with a Board class and move logic, and finally explain the game-over detection algorithm. Emphasize modularity and testability.

Pro tip: Mention that you would separate the core game logic from the UI to make it testable, and discuss how you would handle edge cases like merging multiple tiles in one move. This shows you think about maintainability and correctness.

1. Clarify requirements

Ask about board size (typically 4x4), input method (keyboard, swipe), win condition (2048 tile), and whether to support undo. This ensures you build what's expected.

2. Design data structures

Represent the board as a 2D array (or list of lists) of integers, with 0 for empty cells. Consider using a class to encapsulate board state and operations.

3. Implement move logic

For each direction, slide tiles, merge adjacent equal tiles (only once per move), and add a new random tile (2 or 4) after a successful move. Handle score updates.

4. Detect game over

Check if any empty cells exist or if any adjacent tiles (horizontally or vertically) are equal. If neither, the game is over.

5. Discuss optimizations and trade-offs

Mention potential optimizations like using bitboards for compact representation or precomputing move tables, and trade-offs between simplicity and performance.

Key Points to Mention

  • Board representation: 2D array vs. 1D array vs. bitboard
  • Move algorithm: sliding and merging tiles, ensuring each tile merges only once per move
  • Random tile generation: probability of 2 (90%) vs. 4 (10%)
  • Game-over detection: no empty cells and no adjacent equal tiles
  • Score tracking and win condition (reaching 2048)
  • Separation of concerns: core logic vs. UI for testability

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