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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.
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Showing 2581–2610 of 3640 results
- OpenAIHardSoftware EngineerImplement IP Address Arithmetic
Implement parsing, binary representation, arithmetic offsets, and canonical formatting for both IPv4 and IPv6 addresses and CIDR subnets.
Coding & AlgorithmsOnsitebit-manipulationstring-parsingnetworking - OpenAIMediumData ScientistImplement NumPy neural-network layers
This question tests your ability to implement fundamental neural network components using NumPy, focusing on matrix operations, broadcasting, and numerical stability.
Machine LearningOnsiteNumPyNeural NetworksDeep Learning - OpenAIMediumMachine Learning EngineerImplement Prefix Products and Their Backward Pass
Work through inclusive prefix products in separate-output, in-place, reverse-gradient, and parallel variants. Explain zeros, overflow, mutation and aliasing, constant temporary workspace, synchronization, floating-point effects, and the work/depth trade-offs of each part.
Machine LearningOnsite - 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 - 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 an IPv4 Iterator
This problem tests your ability to handle IPv4 address arithmetic, bitwise operations, and the implementation of a stateful iterator that supports bidirectional traversal and range generation from CIDR notation.
Coding & AlgorithmsOnsiteBit ManipulationIterator PatternNetworking - OpenAIHardSoftware EngineerImplement an in-memory SQL-like table
This question evaluates implementation skills for an in-memory SQL-like table, focusing on data modeling with nested key-value structures, string handling, efficient lookups, and lexicographic sorting with tie-breaking.
Coding & AlgorithmsOnsite - OpenAIHardMachine Learning EngineerImplement in-memory database insert and delete operations
This question evaluates understanding of data structures and algorithmic complexity in the context of designing a key-value in-memory database, and it falls under the Coding & Algorithms domain for a Machine Learning Engineer role while focusing on practical implementation skills.
Coding & AlgorithmsOnsite - OpenAIMediumMachine Learning EngineerImplement vectorized NumPy ops and explain broadcasting
This question evaluates proficiency in vectorized numerical computing with NumPy, understanding of broadcasting semantics, and awareness of numerical stability and algorithmic time/space complexity when manipulating high-dimensional arrays.
Data Manipulation (SQL/Python)Onsite - OpenAIHardMachine Learning EngineerImprove Training With Noisy Annotators
This question evaluates a candidate's ability to handle label noise by estimating annotator reliability and applying data-cleaning, relabeling, or reweighting methods while measuring model performance and understanding classification metrics.
Machine LearningOnsite - 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 - OpenAIMediumMachine Learning EngineerInfer Generic Return Types
Implement a toy type-inference engine that unifies generic parameter types with concrete argument types and substitutes resolved type variables to determine the return type.
Coding & AlgorithmsOnsiterecursiontreetype-systems - OpenAIHardSoftware EngineerLeftmost-Fit Memory Allocator: Allocate Consecutive Units and Free by Owner
Simulate a memory allocator over n units: each allocation takes the leftmost run of consecutive free units for an owner, and each free releases all of that owner's units. Return the result of every operation. It tests interval bookkeeping and logarithmic-time search for free runs at up to 100,000 operations.
Coding & AlgorithmsOnsite - OpenAIHardSoftware EngineerLeftmost-Fit Theater Row Booking With Bulk Cancellation by Group
Simulate booking a single theater row of n seats, where each booking takes the leftmost block of consecutive free seats for a group and a cancellation releases every seat that group currently holds anywhere in the row. Tests augmented-interval bookkeeping and logarithmic-time search for the best free run.
Coding & AlgorithmsOnsitesegment-treeintervalssimulation - OpenAIMediumMachine Learning EngineerMaintain Entropy for a Streaming Distribution
Maintain empirical Shannon entropy after every categorical observation without rescanning all categories. The discussion should cover arbitrary identifiers, first-item behavior, exact counts, floating-point drift, concurrency, deletions, sliding windows, and merging summaries from separate stream partitions.
Statistics & MathOnsite - OpenAIHardSoftware EngineerModel particle hits on a screen
This question evaluates geometric reasoning and probability theory skills, specifically transformation of random variables and derivation of CDF/PDF from angular sampling, together with practical competence in Monte Carlo simulation and interpretation of numerical and visualization artifacts; domain: Software Engineering Fundamentals.
Software Engineering FundamentalsOnsite - OpenAIMediumSoftware EngineerMonitor Devices Over an Unreliable Network
Design an edge-to-cloud device monitoring system that accurately tracks device health and liveness across flaky, high-latency networks without falsely reporting absolute state.
System DesignOnsitesystem-designdistributed-systemsiot - OpenAIHardSoftware EngineerPlant Infection Grid Simulation: Days to Stabilize, Immune Plants, Expiring Immunity
A progressive grid simulation: infection spreads daily between adjacent plants, and you compute how many days the garden takes to stabilize, then add permanently immune plants and immunity that expires after a countdown. It tests multi-source breadth-first search, Dijkstra-style waiting times and precise day counting.
Software Engineering FundamentalsOnsite - OpenAIMediumSoftware EngineerProject Deep Dive: Proving Technical Depth and Cross-Team Alignment
A behavioral project deep-dive question in which you present a past project while the interviewer asks how you aligned with other functional teams and with engineers on your own team, and repeatedly presses on where the technical depth lies. It tests structured storytelling, clear ownership, evidence-backed decisions and composure under challenge.
Behavioral & LeadershipOnsite - OpenAIMediumSoftware EngineerReactive Budget Notebook With Live Formulas and Cycle Rejection
Build a small reactive calculator where named variables hold integers or formulas that reference other variables, values stay correct as inputs change, and any definition that would create a circular dependency is rejected. Tests graph modeling, cache invalidation, cycle detection, and writing tests live.
Software Engineering FundamentalsOnsitedependency-graphcycle-detectioncaching - OpenAIHardMachine Learning EngineerRepair a Broken Tiny Language Model, Then Make Decoding Incremental
Find four planted bugs in a compact PyTorch decoder-only language model (some produce NaNs, some silently ruin learning), then add key/value caching so generation processes one new token per step.
Machine LearningOnsitepytorchtransformersdebugging - OpenAIMediumSoftware EngineerReturn the Lexicographically Smallest Topological Order
Implement a deterministic topological sort using a min-heap to return the lexicographically smallest ordering of a directed graph, or detect cycles and return an empty list.
Coding & AlgorithmsOnsitegraphtopological-sortheap - OpenAIHardMachine Learning EngineerSchedule Incremental Labeling Tasks
This problem tests the ability to design an incremental task scheduler that balances workload across a pool of annotators while maintaining fairness and deterministic state transitions.
Coding & AlgorithmsOnsiteHeapsSchedulingGreedy - OpenAIHardMachine Learning EngineerSearch Monster Battle Strategies
Design a search algorithm using state-space exploration to find the minimum number of turns required to defeat a boss given transient health, scripted boss attacks, and a single-use revive.
Coding & AlgorithmsOnsiteBreadth-First SearchState Space SearchGraph Algorithms - OpenAIHardMachine Learning EngineerSelect high-quality math documents from crawls
This question assesses the ability to design a scalable pipeline that ingests, cleans, extracts, and filters high-quality mathematical content from diverse, noisy web-crawled sources.
ML System DesignOnsiteSystem DesignNLPData Engineering - OpenAIHardMachine Learning EngineerSimulate Plant Infection With Controlled Burning
This question evaluates a candidate's ability to implement discrete-time grid simulations with delayed state transitions, reason about simultaneous updates and neighborhood effects, and perform a limited combinatorial optimization (choosing one row or column) to minimize a global outcome.
Coding & AlgorithmsOnsite - OpenAIMediumMachine Learning EngineerSimulate Turn-Based Monster Battles
This problem tests your ability to design a stateful simulation engine that handles turn-based mechanics, complex status modifiers, and dynamic combat interactions.
Coding & AlgorithmsOnsiteSimulationState ManagementGame Logic - OpenAIMediumSoftware EngineerSliding-Window Chat Analytics: Recent Counts, Live Sessions, Out-of-Order Events
A three-part coding exercise: build an in-memory chat analytics service that counts each chat's interactions in a closed 15-minute sliding window, tracks each user's live sessions from touch and close events, and stays correct when events arrive out of order. It tests bounded-memory eviction, efficient updates and queries, and exact window and ordering semantics.
Software Engineering FundamentalsOnsite
OpenAI