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Zipline·Software Engineer·Onsite - Coding / Algorithms·Senior

Senior
Jun 2026

Summary

Zipline robotics coding round where you build a checkers game simulation collaboratively with the interviewer in about an hour. The architecture design piece came first, then they jumped in to co-write some functions while I was expected to own the core algorithm modules. Felt less like a solo grind and more like a pair programming session, which I wasn't fully prepared for.

Questions Asked (1)

Q1

Design and implement a checkers game simulation with clean object-oriented architecture, then build out the core game logic modules collaboratively with the interviewer.

System DesignAlgorithms & Data StructuresTechnical Trade-offs
Author's notes

The OOP design part was fine but I underestimated how much they'd scrutinize interface definitions before letting us move forward.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and scope, then sketch a clean object-oriented design with clear separation of concerns (board, pieces, rules, game state). Implement core logic incrementally, validating each module with the interviewer before moving on, and discuss trade-offs as you go.

Pro tip: Treat the interviewer as a collaborator: pause after each module to explain your reasoning and invite feedback, showing you value iterative development and communication over silent coding.

1. Clarify Requirements and Scope

Ask questions to define the game rules (e.g., mandatory captures, king promotion, board size) and constraints (e.g., time, language, testing). Confirm the expected level of detail for the simulation.

2. Design the Object Model

Identify core classes (Board, Piece, Player, Move, Game) and their responsibilities, relationships, and interfaces. Sketch a UML-like diagram or list key methods to ensure clean separation of concerns.

3. Implement Core Modules Incrementally

Start with the board and piece representation, then add move validation, capture logic, and turn management. After each module, explain your code and check with the interviewer before proceeding.

4. Test and Validate Logic

Write unit tests or walk through edge cases (e.g., multiple captures, king movement, win conditions) to verify correctness. Discuss how you would handle testing in a real codebase.

5. Discuss Trade-offs and Extensions

Reflect on design decisions (e.g., inheritance vs. composition, mutable vs. immutable state) and suggest possible extensions (e.g., AI opponent, networked play) to show forward thinking.

Key Points to Mention

  • Separation of concerns: board state, piece behavior, and game rules should be distinct classes or modules.
  • Use of design patterns: e.g., Strategy for move validation, State for game phases, or Factory for piece creation.
  • Encapsulation: hide internal board representation and expose only necessary methods.
  • Extensibility: design so that new rules or piece types can be added with minimal changes.
  • Testing: emphasize unit tests for move generation, capture logic, and win conditions.
  • Trade-offs: discuss performance vs. simplicity, and how to handle complex rules like mandatory captures.

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