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Software Engineering Fundamentals Interview Questions
Practice 9403 coding, system design and machine learning questions from 546 companies, sorted by role, topic and interview round. Every question has step-by-step hints, a code runner that supports 8 languages and an AI mentor; members also get the full solution walkthrough.
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Showing 781–810 of 1208 results
- OpenAIHardMachine Learning EngineerDesign an Extensible Simulation Engine
This problem tests object-oriented design patterns and modular architecture by requiring the implementation of a simulation engine that remains agnostic to the specific rules of a two-player turn-based game.
Software Engineering FundamentalsOnsiteSystem DesignObject-Oriented DesignDesign Patterns - OpenAIHardMachine Learning EngineerDesign an In-Memory Key-Value Cache
Implement a thread-safe in-memory key-value cache supporting capacity bounds, LRU eviction, and per-key time-to-live (TTL) expiration.
Software Engineering FundamentalsTechnical ScreenData StructuresConcurrencyLRU Cache - OpenAIMediumSoftware EngineerDispatch Parcels to Delivery Drones That May Go Silent Mid-Flight
Build an in-process dispatcher that hands delivery parcels to drones, reclaims a parcel when its drone goes silent, rejects stale reports from a drone that already lost its parcel, and quarantines parcels that fail too many times.
Software Engineering FundamentalsTechnical Screenconcurrencystate-machinereliability - OpenAIHardSoftware EngineerDurable Session Cache: Byte Checkpoints, Segments, Thread Safety
A three-part exercise building a durable in-memory session cache: serialize entries to length-prefixed bytes and checkpoint them to disk, split the checkpoint into size-capped segments that reassemble by concatenation, then discuss making the class thread-safe. Tests byte-level encoding, exact round-tripping, and concurrency reasoning.
Software Engineering FundamentalsTechnical Screenserializationpersistenceconcurrency - OpenAIMediumSoftware EngineerExpiring GPU Credit Ledger with Out-of-Order Events and Point-in-Time Balance
A two-part coding exercise to build a GPU credit ledger with expiring grants, usage deducted earliest-expiration-first, out-of-order events and balance queries at any timestamp, then avoid replaying from time zero on every query. It tests event ordering, heap use, checkpointing and invalidation when late events arrive.
Software Engineering FundamentalsTechnical Screen - OpenAIHardSoftware EngineerExplain JS threading and useState vs useRef
This question evaluates understanding of JavaScript's execution model and concurrency mechanisms (including worker-based threading) along with React state-management semantics, specifically the behavioral differences between useState and useRef.
Software Engineering FundamentalsHR Screen - OpenAIMediumMachine Learning EngineerExplain KV cache in Transformer inference
This question evaluates understanding of KV cache mechanisms in Transformer inference, including attention-state caching, memory and latency trade-offs, and engineering optimizations for autoregressive decoding.
Software Engineering FundamentalsOnsite - OpenAIHardMachine Learning EngineerExplain what torch.distributed.barrier does
This question evaluates understanding of PyTorch distributed synchronization primitives, process coordination, and concurrency control in distributed training workflows.
Software Engineering FundamentalsOnsite - OpenAIMediumApplied ScientistExtensible card-hand ranking: three of a kind, flush, pair and a discard rule
A three-part object-oriented coding exercise built around a card game: rank hands by three of a kind, pair and high card, insert a flush category, then add a discard rule that removes hands that are not a pair, returning a log of each game. It tests extensible design, deterministic tie-breaking and absorbing rule changes cleanly.
Software Engineering FundamentalsOnsite - OpenAIHardSoftware EngineerFault-Tolerant Task Queue with Retries, a Dead-Letter Queue and Task Dependencies
Implement an in-memory fault-tolerant task queue with enqueue, reserve, complete and fail operations, retries up to a configurable attempt limit, and a dead-letter queue for tasks that keep failing. A second part adds dependencies between tasks, testing state-machine design, efficient readiness tracking and handling of failed dependencies.
Software Engineering FundamentalsTechnical Screen - OpenAIHardSoftware EngineerFault-Tolerant Task Queue with Retry Cooldowns, a Dead-Letter Queue and Dependencies
Implement an in-memory fault-tolerant task queue with enqueue, reserve, fail and a dead-letter queue, where each failed task waits out its own cooldown measured from the failure time and returns in its original enqueue order. A second part adds task dependencies, testing state modeling, efficient scheduling and careful edge-case handling.
Software Engineering FundamentalsTechnical Screen - OpenAIHardSoftware EngineerFault-Tolerant Work Queue with Leases, Fencing Tokens and DAG Task Dependencies
Implement a fault-tolerant work queue in which workers claim tasks under expiring leases, crashed workers' tasks are reassigned, and late reports from stale workers are rejected, then add DAG dependencies with cycle detection. It tests leases, fencing tokens, topological release and delivery semantics.
Software Engineering FundamentalsOnsite - OpenAIHardSoftware EngineerFind a Hidden Number When Each Comparison Answer Arrives One Call Late
Find a hidden integer from 1 to n using a comparison API whose answers arrive one call late: each call submits a new guess but returns the result for the previous one. Build a correct search first, then reduce the worst-case number of calls. It tests binary search under delayed feedback and worst-case analysis.
Software Engineering FundamentalsOnsite - OpenAIHardSoftware EngineerFollow Graph with Cheap Snapshots and Top-K Follow Recommendations
Build a one-directional follow graph that supports cheap snapshots and queries against past snapshots, then recommend the top k accounts a user should follow. It tests versioned data structures, snapshot semantics, two-hop graph traversal, heap-based top-k selection and scaling to highly connected accounts.
Software Engineering FundamentalsOnsite - OpenAIHardSoftware EngineerGPU Credit Ledger with Expiring Grants, Out-of-Order Operations and Fast Balances
Implement a GPU credit ledger with expiring grants, subtractions that spend the soonest-expiring credits first, and balance queries, where operations can arrive out of timestamp order. Then avoid recomputing from time zero on every query. It tests event replay, priority queues and checkpoint invalidation.
Software Engineering FundamentalsOnsite - OpenAIMediumSoftware EngineerGPU Credit Ledger: Spend Earliest-Expiring Credits First, Stop on Overdraft
A coding and design question about an in-memory GPU credit ledger that grants expiring credits, charges usage against the credit that expires soonest, and returns no balance once any charge overdraws the account. It tests data structure choice, expiry and boundary conventions, and optimizing the ledger for a very large number of credit changes.
Software Engineering FundamentalsOnsite - OpenAIMediumSoftware EngineerGame Telemetry Windows: Match Counts, Live Sessions, Late Events
Build an in-memory service that counts per-match actions inside a global 10-minute window, tracks each player's live client sessions from heartbeats and logouts, and stays correct when events arrive late. Tests bounded-memory eviction, amortized analysis, lazy deletion and exact window semantics.
Software Engineering FundamentalsOnsitesliding-windowheapqueue - OpenAIMediumiOS EngineerImplement A Mobile Chat Interface In An Existing Codebase
Tests your ability to design and implement a streaming chat interface state manager in an existing mobile codebase, focusing on async token streaming, state modeling, cancellation, and error handling.
Software Engineering FundamentalsTechnical ScreeniOSSwiftConcurrency - OpenAIMediumSoftware EngineerImplement a GPU credit ledger with expiring grants and out-of-order operations
Implement a GPU credit ledger with grant, subtract and get-balance operations, where grants expire and spending draws from the soonest-expiring grant first. Operations can arrive out of timestamp order, and a follow-up asks how to avoid replaying the whole history from time zero on every query in production.
Software Engineering FundamentalsOnsite - OpenAIMediumSoftware EngineerImplement a Recoverable In-Memory Key-Value Store
This problem tests your understanding of durability, logging, and data persistence in an in-memory system.
Software Engineering FundamentalsTechnical ScreenSystemsConcurrencyPersistence - OpenAIHardSoftware EngineerImplement a Set with Readable Snapshots
Design and implement a versioned set data structure that supports membership modifications, instant snapshotting, and historical point-in-time queries efficiently.
Software Engineering FundamentalsOnsiteData StructuresDesignBinary Search - OpenAIMediumSoftware EngineerImplement a Simple Memory Allocator
This question evaluates low-level memory management and allocator design skills, including block header layout, free-list/data-structure choices, pointer arithmetic, fragmentation concepts, and analysis of time/space complexity.
Software Engineering FundamentalsOnsite - OpenAIMediumSoftware EngineerImplement a fault-tolerant work queue that never loses tasks when workers fail
Implement an in-process work queue that never loses a task when the worker holding it crashes, stalls or reports an error. It tests task state tracking, detecting silent workers, rejecting late reports from workers that lost a task, bounded retries for tasks that always fail, thread safety, and deterministic tests built on an injected clock.
Software Engineering FundamentalsTechnical Screen - OpenAIMediumSoftware EngineerImplement an Extensible Chatbot App
This question evaluates a candidate's ability to design extensible object-oriented systems, covering interface-based architecture, dependency injection, per-conversation state management, and decoupled dispatch logic.
Software Engineering FundamentalsTechnical Screen - OpenAIHardSoftware EngineerImplement malloc and free over Fixed Memory, Then Make Both Logarithmic
Implement malloc and free for a fixed range of memory in Python, first with a simple list of blocks and then with logarithmic-time operations backed by a third-party sorted container. It tests block splitting and merging, choosing ordered indexes for allocation and neighbor lookup, and keeping parallel structures consistent.
Software Engineering FundamentalsTechnical Screen - OpenAIHardSoftware EngineerIn-Memory Key-Value Store with Crash Recovery from a Log and Concurrent Access
Implement an in-memory key-value store, make it recover from a log file after a crash, including a half-written final record, and make it correct and fast under many concurrent threads. It tests write-ahead logging, crash consistency, compaction, and lock design with group commit.
Software Engineering FundamentalsOnsite - OpenAIHardSoftware EngineerIndexed Vector as a Linked List with Checkpoints Every k Nodes
Implement an indexed dynamic sequence of strings, in the sense of an array list, that supports inserting at a position and reading by position. Starting from a plain singly linked list, build a linked list with a checkpoint every k nodes so reads cost O(k), and keep the checkpoints correct as insertions shift positions.
Software Engineering FundamentalsOnsite - OpenAIHardSoftware EngineerKey-Value Store Persistence: Length-Prefixed Bytes, Size-Capped Chunks, Thread Safety
A three-part key-value store exercise: serialize keys, values and their lengths into bytes and persist them on shutdown, split the saved data into chunks of a given maximum size, and discuss making the existing code safe for multithreaded use. It tests byte-level encoding, correct restore and concurrency reasoning.
Software Engineering FundamentalsTechnical Screen - OpenAIHardSoftware EngineerLab Robot Job Dispatcher with Backoff, Quarantine and Prereqs
Implement an in-memory job dispatcher where failed jobs wait out a per-job backoff, keep their original queue position, and get quarantined after repeated failures, then add prerequisite jobs with cascading quarantine. Tests state modeling, dual-heap scheduling, and online topological ordering.
Software Engineering FundamentalsTechnical Screenheapschedulingstate-machine - OpenAIMediumSoftware EngineerLease-Based Job Queue for Flaky Render Workers
Build an in-process job queue that hands out time-limited leases. A job is never lost when a worker crashes, hangs or fails, and jobs that always fail are dead-lettered after a retry limit. Tests state machines, fencing tokens, thread safety and clock-injected tests.
Software Engineering FundamentalsTechnical Screenconcurrencyqueuesfault-tolerance
OpenAI