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OpenAI pairs an unusually high raw-coding bar with explicit no-AI-tools rules during most interviews — a deliberate contrast with the product. Phone screens often run a single multi-part simulation for the full hour, and senior loops add deep ML and research-grounded system-design rounds that probe mechanism, not vocabulary.

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Coding·60 min
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Infection Spread / Cellular Automata

M×N grid with infected cells (X) and susceptible cells (./*); infection propagates each day under escalating rules. 5 sub-parts in 60 min; passing bar is typically solving the first 3 with clean BFS.

SWE
MLE
RE
RS
algorithm
simulation
bfs
medium
Last asked 2026-07-1838 related discussions

OJ Problems

practice in the online judge
144 total
Friend Circles / Number of ProvincesCount Machines in a Cluster Tree and Recover Tree TopologySharded Matrix Multiplication and BackpropagationImplement a Simple Memory Allocator with First-Fit and Best-FitImplement Masked Cross Entropy Loss with Label SmoothingMaximum Falling Path with Limited Vertical Jumps and Bonus ScoringIn-Memory Memory Allocator with malloc/free, First-Fit and Best-FitMessage Event Aggregation in a 5-Minute Sliding WindowBuild a ChatGPT Chat Interface in an Existing iOS ProjectFind the Incorrect Data LabelerMinimum Time to Infect a NetworkRestore Valid IPv4 AddressesPlant Infection by Neighbor CountInfection Spread with Immune Units and Expiring ContagiousnessStreaming Entropy with Online and Block-wise UpdatesResumable Iterator for List and FileMinimum Time to Infect All PlantsReproduce Double Descent in Linear RegressionImplement malloc and free with First-Fit Allocation and Discuss Best-Fit OptimizationCell Simulation / Conway's Game of LifeDesign a Memory Allocator with CoalescingCoding: Design a Distributed Rate Limiter with Persistence (Clock Skew, Redis Fallback)Debug A/B Test Python Code (Metric Computation and Statistical Testing)Basic SQL Querying (Filtering, Aggregation, Join, Window Functions)Draw Paths / Strokes on a Set of PointsMachine Topology Reasoning (Topology / Dependency Graph)Social Network Query/Computation (Graph-Based Social Problem)Infection Spread on a Network (Graph Propagation)Plant Infection (multi-part)Infectious Disease Simulation / Containment (unspecified)

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