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Openai·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Apr 2026

Summary

OpenAI software engineer coding round, one problem with multiple sub-parts centered on epidemic/disease spread simulation. Got through three of the sub-problems before the interviewer cut it off, which stung a little since there was still time left on the clock.

Questions Asked (1)

Q1

Simulate the spread of an infectious disease through a population. The problem had multiple sub-parts building on each other.

Algorithms & Data StructuresSystem Design
Author's notes

I'd actually prepped for this general topic so it wasn't a total blindside.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem scope and assumptions, then propose a simple compartmental model (e.g., SIR) and iteratively extend it to address sub-parts like network effects, interventions, and scalability. Discuss trade-offs between model complexity and computational feasibility, and outline how you would validate and test the simulation.

Pro tip: Demonstrate awareness of real-world constraints by discussing how you would handle large populations (e.g., using approximate methods or parallelization) and how you would validate the model against historical data or known epidemiological properties.

1. Clarify Requirements and Assumptions

Ask questions to understand the population structure, disease parameters, and expected outputs. Define assumptions about homogeneity, mixing, and time steps.

2. Choose a Model

Select an appropriate model (e.g., SIR, SEIR, network-based) based on requirements. Explain the compartments, transitions, and equations governing the spread.

3. Design the Simulation

Outline the data structures (e.g., arrays for states, adjacency list for networks) and algorithm (e.g., discrete-time steps, event-driven). Discuss initialization and parameter setting.

4. Address Sub-parts and Extensions

For each sub-part (e.g., interventions, age structure, stochasticity), describe modifications to the model and simulation. Discuss how to incorporate them without redesigning from scratch.

5. Analyze Scalability and Validation

Discuss computational complexity, potential optimizations (e.g., sampling, parallelization), and how to validate results (e.g., consistency checks, comparison with analytical solutions).

Key Points to Mention

  • Compartmental models (SIR/SEIR) and their equations
  • Stochastic vs deterministic simulation
  • Network-based models for heterogeneous mixing
  • Interventions (vaccination, quarantine) and their impact
  • Computational complexity and optimization techniques
  • Validation against real-world data or theoretical results

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