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Amazon·Software Engineer·Onsite - System Design / Architecture·Senior

Senior
May 2026

Summary

Amazon system design round for a software engineer role. The whole session was basically one big question about designing Minesweeper as a fully interactive game system, and it went deeper than I expected.

Questions Asked (1)

Q1

Design Minesweeper as an interactive game system with configurable board dimensions, mine placement, and a full set of game APIs.

System DesignTechnical Trade-offsAlgorithms & Data Structures
Author's notes

I started with the API surface which felt natural: new_game, reveal, flag, state.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints, then design the core data model and algorithms for board generation and gameplay. Define clean APIs for game actions and state, and discuss trade-offs around scalability, performance, and user experience.

Pro tip: Emphasize the importance of a clean separation between game logic and presentation, and discuss how you would handle edge cases like first-click safety and efficient mine placement.

1. Clarify Requirements

Ask questions to understand expected scale, features (e.g., flags, timer, difficulty levels), and constraints (e.g., board size limits, performance targets).

2. Design Data Model

Define how to represent the board, cells, mines, and game state. Consider using a 2D array or sparse representation for large boards.

3. Define Core Algorithms

Outline algorithms for mine placement (ensuring first-click safety), revealing cells (with flood fill for empty regions), and win/loss detection.

4. Specify APIs

List the key operations: create game, reveal cell, toggle flag, get game state, reset. Define inputs, outputs, and error handling.

5. Discuss Trade-offs and Extensions

Talk about performance (time/space), scalability (e.g., multiplayer, persistence), and potential optimizations like lazy mine placement.

Key Points to Mention

  • First-click safety: ensure the first revealed cell is never a mine, often by placing mines after the first click.
  • Flood fill algorithm for revealing adjacent empty cells efficiently, using BFS/DFS with a queue/stack.
  • Data structures: 2D array for board, bitmask or separate arrays for mine locations and revealed state.
  • API design: clear separation of concerns, idempotent operations, and proper error handling for invalid moves.
  • Trade-offs: memory vs. speed for large boards, and whether to precompute mine counts or compute on the fly.
  • Extensibility: how to add features like difficulty levels, timers, or multiplayer without major refactoring.

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