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Openai·Software Engineer·Technical Phone Screen·Senior

Senior
Apr 2026

Summary

OpenAI SWE interview with a multi-part coding problem centered on simulating infectious disease spread across five incremental sub-questions. The problem built on itself each round, which was an interesting format I hadn't seen before.

Questions Asked (1)

Q1

Implement a multi-part simulation of infectious disease spread, broken into 5 incremental sub-questions that build on each other.

Algorithms & Data StructuresSystem DesignTechnical Trade-offs
Author's notes

The structure was the tricky part.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the 5 sub-questions and their dependencies, then design a modular simulation with clear interfaces. Implement incrementally, validating each part before moving on, and discuss trade-offs (e.g., performance vs. accuracy) at each step.

Pro tip: Proactively discuss how you would test and validate each sub-question, including edge cases and scalability, to demonstrate engineering maturity.

1. Clarify requirements and scope

Ask questions to understand the expected inputs, outputs, and constraints for each sub-question. Confirm the disease model (e.g., SIR), population structure, and time steps.

2. Design modular architecture

Outline a modular design with separate components for population, disease states, and simulation loop. Define interfaces to allow incremental extension.

3. Implement incrementally

Code each sub-question one by one, starting with the simplest. Test each part thoroughly before integrating with the next.

4. Analyze trade-offs

For each sub-question, discuss time/space complexity, accuracy vs. performance, and potential optimizations (e.g., spatial partitioning, parallelization).

5. Validate and iterate

Run simulations with known scenarios to validate results. Discuss how to handle edge cases and scale to larger populations.

Key Points to Mention

  • Choice of epidemiological model (e.g., SIR, SEIR) and its assumptions
  • Data structures for efficient neighbor queries (e.g., grid, k-d tree)
  • Handling of stochastic vs. deterministic simulation
  • Time complexity and scalability concerns for large populations
  • Testing strategies including unit tests and validation against analytical solutions
  • Potential extensions like vaccination, age structure, or network topology

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