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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.
- 9403
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- 546
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- 11
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- 8
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Showing 3061–3090 of 4616 results
- OpenAIMediumSoftware EngineerMinimize deaths in spreading plant infection
This problem tests your ability to simulate a state-based grid propagation and optimize intervention timing using either greedy or dynamic programming approaches.
Coding & AlgorithmsTechnical ScreenSimulationBFSGrid - OpenAIMediumMachine Learning EngineerModel Infection, Immunity, Delayed Death, and Burn Interventions on a Grid
Design and implement a discrete grid simulation modeling a five-stage disease progression with state countdowns, immunity, delayed mortality, and external burn interventions.
Software Engineering FundamentalsTechnical Screensimulationmatrixstate-machine - OpenAIMediumSoftware EngineerOptimize C++ Performance with Provided Concurrency
This question evaluates a developer's skills in C++ performance engineering and concurrent systems, covering profiling, bottleneck identification (e.g., cache locality and lock contention), and code-level performance reasoning to improve throughput and latency.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerOrder Recipe Prep Steps Into the Smallest Valid Sequence
Return a deterministic, lexicographically smallest valid ordering of named prep steps with dependency constraints, correctly including steps with no prerequisites and steps unconnected to any dependency.
Coding & AlgorithmsTechnical Screentopological-sortgraphsheap - OpenAIMediumSoftware EngineerOrder Tasks with Dependencies Using a Deterministic Topological Sort
Tests deterministic topological sorting of a directed acyclic graph using Kahn's algorithm and a priority queue to guarantee lexicographical tie-breaking.
Coding & AlgorithmsTechnical Screengraphtopological-sortheap - OpenAIMediumSoftware EngineerParse and build binary data in Python
This question evaluates proficiency in binary data handling and serialization/deserialization in Python, including little-endian integer encoding, length-prefixed payloads, robust error handling for short reads and invalid lengths, and testability and performance considerations.
Data Manipulation (SQL/Python)Technical Screen - OpenAIHardSoftware EngineerPrint Shop Job Queue: Retries, a Poison Queue and Job Prerequisites
Implement an in-memory job queue for a print shop where workers reserve, complete, or fail jobs, failed jobs retry up to a limit before landing in a poison queue, and a second part adds job prerequisites with cascading failure.
Software Engineering FundamentalsTechnical Screenqueuesstate-machinesretries - OpenAIHardSoftware EngineerReason About Binary Search with One-Call-Delayed Feedback
Implement and analyze binary search under a 1-step delayed-feedback protocol where each query response evaluates the previous guess.
Software Engineering FundamentalsTechnical Screenbinary-searchinteractivealgorithms - OpenAIMediumSoftware EngineerRebalance shard ranges under overlap limit
This problem tests interval manipulation and greedy optimization by requiring you to adjust a set of shard ranges so that no more than k ranges overlap at any integer point, while minimizing the number of boundaries moved.
Coding & AlgorithmsTechnical ScreenAlgorithmsSweep-LineIntervals - OpenAIMediumSoftware EngineerRefactor a Chatbot into Clean Object-Oriented Components
Tests object-oriented design and refactoring skills by decoupling a monolithic chatbot script into modular, testable, and extensible components adhering to SOLID principles.
Software Engineering FundamentalsTechnical ScreenObject-Oriented DesignRefactoringDesign Patterns - OpenAIHardSoftware EngineerRefactor a chat message processing function
This problem tests your ability to refactor procedural, error-prone code into a robust, extensible pipeline for parsing and managing chat message state.
Coding & AlgorithmsTechnical ScreenRefactoringString-ManipulationOOP - OpenAIHardSoftware EngineerResolve Short-Link Redirect Chains That May Loop
Follow single-target redirects from a start code and return the final code, or the last code before the walk would revisit one. Then answer many starts in linear total time. Tests visited-set bookkeeping and functional-graph structure.
Coding & AlgorithmsTechnical Screengraphsfunctional-graphcycle-detection - OpenAIHardSoftware EngineerRotate Couriers Daily at Minimum Total Cost
Choose one courier company per day so that no company works two days in a row and the total price is minimal, then return the schedule. Tests DP over a small state, path reconstruction, and the best/second-best trick for k options.
Coding & AlgorithmsTechnical Screendynamic-programmingreconstructionarrays - OpenAIMediumSoftware EngineerSerialize and Restore an In-Memory Key-Value Store
Design and implement a deterministic binary serializer and strict deserializer for a string key-value store, ensuring robust input validation against corruption, truncation, duplicate keys, and trailing data.
Software Engineering FundamentalsTechnical Screenbinary-serializationsystemsdata-encoding - OpenAIHardMachine Learning EngineerSimulate Infection Spread on a Grid
Implement a discrete-time cellular automaton simulating epidemic spread on a 2D grid with multi-day infection states, immunity waning, and mortality rules.
Coding & AlgorithmsTechnical ScreenSimulationMatrixCellular Automata - OpenAIMediumMachine Learning EngineerSimulate Infection Spread with Immunity and Recovery
Implement a cellular automaton simulation modeling disease spread on a 2D grid with discrete cell states and timed recovery.
Coding & AlgorithmsTechnical ScreenGrid SimulationCellular AutomataBFS - OpenAIEasySoftware EngineerSimulate a Turn-Based Two-Player Game
This problem tests your ability to design a robust state management system and implement validation logic for a rule-based game.
Coding & AlgorithmsTechnical ScreenState ManagementAPI DesignSimulation - OpenAIMediumSoftware EngineerSocial Graph with Follow/Unfollow, Snapshots, History Queries and Recommendations
A software engineer phone-screen coding problem: build an in-memory social graph that supports follow and unfollow, point-in-time snapshots, queries of who followed whom as of an earlier snapshot, and recommendations of users to follow. It tests data-structure choice, versioned history, and deterministic ranking.
Software Engineering FundamentalsTechnical Screen - OpenAIMediumSoftware EngineerSpreading Contagion on a Grid
Tests modeling multi-source breadth-first search (BFS) on a 2D grid to compute simultaneous state propagation across discrete time steps.
Coding & AlgorithmsTechnical Screenmulti-source-bfsgraphsmatrix - OpenAIHardMachine Learning EngineerStreaming Entropy with Numerical Stability
Implement an online, numerically stable algorithm to compute Shannon entropy over an unbounded stream of categorical tokens with O(1) updates.
Coding & AlgorithmsTechnical Screenstreamingmathnumerical-computing - OpenAIMediumSoftware EngineerThree-Card Game: Deal Hands, Rank Them, Then Add a Flush Category
A two-part card game coding exercise: deal three cards to each player from one deck, show every hand and pick the winner using three of a kind, pair and high card, then add a flush category between them. It tests hand representation, within-category comparison, tie handling and code that extends cleanly when a rule changes.
Software Engineering FundamentalsTechnical Screen - OpenAIHardMachine Learning EngineerTrain a classifier and analyze dataset
This question evaluates proficiency in end-to-end supervised machine learning workflows—covering data validation, exploratory data analysis, preprocessing, model training and selection, evaluation metrics and calibration, fairness assessments, and reproducibility—and tests competencies in applied machine learning engineering, statistical reasoning, and model governance within the Machine Learning domain. It is commonly asked in technical interviews because it verifies practical implementation skills and judgment for deploying reliable classifiers, aligning metrics to business goals and diagnosing performance and fairness across slices, with emphasis on practical application informed by conceptual understanding.
Machine LearningTechnical Screen - OpenAIMediumMachine Learning EngineerTrain and analyze a classifier
This question evaluates proficiency in end-to-end machine learning engineering, including exploratory data analysis, time-aware train/validation/test splitting, model baseline and improvement, class imbalance strategies, leakage-safe hyperparameter tuning, metric computation and calibration, error analysis, reproducible training pipelines with CLI/config/seed control, explainability (feature importance/SHAP and ablations), and documentation of risks, fairness checks and monitoring hooks. It is commonly asked to assess practical ability to manage the full ML lifecycle and data hygiene in production-like scenarios, testing applied Data Manipulation (SQL/Python) and Machine Learning competencies with an emphasis on practical application while also requiring conceptual understanding of evaluation, calibration and fairness.
Data Manipulation (SQL/Python)Technical Screen - OpenAIMediumMachine Learning EngineerVectorize One-Nearest-Neighbor and Express It as a Neural Forward Pass
Tests vectorized distance computation in array libraries and the mathematical equivalence between nearest-prototype classification and an affine neural network layer.
Machine LearningTechnical Screenvectorizationnearest-neighborslinear-algebra - OpenAIHardData ScientistWrite SQL for repeat churn
This question evaluates proficiency in event-time analytics and cohort churn metric computation using SQL, focusing on correct identification of first qualifying events and aggregation by experimental variant.
Data Manipulation (SQL/Python)Technical Screen - OpenAIMediumData ScientistWrite SQL to compute signup and retention lift
This prompt evaluates SQL proficiency in time-windowed cohort analysis, event deduplication, date arithmetic, and per-variant aggregation for A/B experiments, categorized under Data Manipulation (SQL/Python) and targeted at an intermediate-level Data Scientist role.
Data Manipulation (SQL/Python)Technical Screen - OpendoorMediumBackend EngineerDesign Map-Based Home Search
This problem tests the ability to design a geo-spatial search service capable of handling high-frequency map interactions, filtering, and data consistency at scale.
System DesignTechnical ScreenGeo-spatialCachingScaling - OpendoorHardBackend EngineerExecute a TTL Key-Value Store with Transactions
This problem tests the implementation of an in-memory key-value store supporting TTL expiration, atomic transactions with rollback capabilities, and logical time-based validation.
Coding & AlgorithmsTechnical ScreenHashMapsTransactionsTTL - OptiverHardData ScientistAnalyze EV, arbitrage, and bet sizing across games
This question evaluates proficiency in probability and statistics—particularly expected value and variance computation, arbitrage detection across payoff tables, quantitative bet-sizing strategies (e.g., Kelly and fractional sizing), and numerical approximation skills for independent discrete outcomes.
Statistics & MathTechnical Screen - OptiverHardSoftware EngineerAnalyze an Unfair-Coin Bankroll Game
This problem tests probability theory and expected value calculations in the context of a game with an unfair coin and a bankroll constraint.
Statistics & MathTechnical ScreenProbabilityExpected ValueRecurrence Relations
OpenAI
Optiver