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Openai·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Interviewed for a SWE role at OpenAI, got a simulation-style coding problem involving infection spread. Not a lot to say since the details are fuzzy in my memory now, but it was a technical screen of some kind.

Questions Asked (1)

Q1

Simulate how an infection spreads through a population or grid over time.

Algorithms & Data Structures
Author's notes

I remember it being a grid traversal type problem but I can't recall the exact constraints.

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AI HintsAI Generated

Suggested Approach

Model the population as a grid or graph where each node has a state (susceptible, infected, recovered). Simulate time steps, updating states based on infection and recovery probabilities, and track the spread. Discuss trade-offs between different models and optimizations for large populations.

Pro tip: Clarify assumptions early (e.g., homogeneous mixing, fixed infection rate) and mention that the model can be extended to include vaccination, immunity, or network effects. This shows you think beyond the basic simulation.

1. Clarify Requirements and Assumptions

Ask about the population structure (grid, graph, or well-mixed), parameters (infection rate, recovery rate), and time granularity. State your assumptions clearly.

2. Choose a Model

Select a model like SIR (Susceptible-Infected-Recovered) or SEIR, and decide on the spatial representation (e.g., 2D grid with Moore neighborhood).

3. Design the Simulation Algorithm

Outline the step-by-step process: initialize states, iterate over time steps, compute new states based on neighbors and probabilities, and handle recoveries.

4. Implement and Optimize

Write pseudocode or code, using efficient data structures (e.g., arrays for grids, adjacency lists for graphs). Discuss optimizations like parallelization or sparse updates.

5. Validate and Analyze Results

Test with small cases, visualize the spread, and compute metrics like peak infection rate or total infected. Discuss how to validate against real-world data.

Key Points to Mention

  • Choice of epidemiological model (SIR, SEIR, etc.) and its parameters.
  • Spatial representation: grid vs. graph, and neighborhood definitions (e.g., von Neumann vs. Moore).
  • Time-stepping simulation and state transition rules.
  • Data structures for efficiency (e.g., 2D array, adjacency list, hash map for sparse populations).
  • Optimizations: parallelization, vectorization, or event-driven simulation for large-scale scenarios.
  • Extensions: vaccination, immunity, network topology, and stochastic vs. deterministic modeling.

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