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Openai·Software Engineer·Technical Phone Screen·Senior

SeniorPrefer not to say
Jun 2026

Summary

Did a technical screen for a Software Engineer role at OpenAI. The whole thing was one big OOD problem around simulating a turn-based monster battle. More design-heavy than I expected for a phone screen.

Questions Asked (1)

Q1

Design an object-oriented model and implement the core battle logic for a turn-based fight between two teams of monsters. The system should simulate the battle round by round and produce a detailed chronological battle log plus a final result.

System DesignAlgorithms & Data StructuresData Modeling
Author's notes

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and defining the core domain model (Monster, Team, Battle, Turn) with clear responsibilities and extensibility points. Then outline the battle loop, turn order, action resolution, and logging, and finally discuss implementation details, edge cases, and testing.

Pro tip: Emphasize separation of concerns: keep battle logic independent of logging and I/O, and use dependency injection for randomness and time to make the system testable and deterministic.

1. Clarify Requirements and Scope

Ask about team sizes, monster attributes, turn order rules, win conditions, and log format. Confirm whether abilities, status effects, or items are needed.

2. Design the Domain Model

Define classes like Monster, Team, Battle, Turn, Action, and Logger. Assign responsibilities and relationships, focusing on encapsulation and extensibility.

3. Define Battle Flow and Turn Logic

Specify how turns are ordered (e.g., by speed), how actions are chosen and resolved, and how damage/effects are applied. Handle edge cases like simultaneous death.

4. Implement Logging and Result Reporting

Design a logger that records each event chronologically with sufficient detail. Ensure the final result (winner, survivors, rounds) is clearly reported.

5. Discuss Extensibility, Testing, and Trade-offs

Mention how to add new abilities or monster types via polymorphism. Describe unit tests for battle logic and trade-offs between simplicity and flexibility.

Key Points to Mention

  • Encapsulation of monster state and behavior, with methods like attack, takeDamage, and isAlive.
  • Turn order determination (e.g., initiative/speed) and handling ties.
  • Action resolution: damage calculation, hit/miss, critical hits, and status effects.
  • Chronological battle log with timestamps, actor, action, target, and outcome.
  • Win condition: one team eliminated or max rounds reached; final result summary.
  • Design patterns: Strategy for actions, Observer for logging, Factory for monster creation.

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