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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 6361–6390 of 9403 results
- OpenAIHardMachine Learning EngineerImplement a 1-Nearest-Neighbor Classifier with a Manhattan-Distance Follow-Up
Implement a 1-nearest-neighbor classifier that labels each query point with the label of its closest training point under Euclidean distance, then extend it to Manhattan distance. Tests vectorized distance computation under memory limits, tie handling and how the choice of metric changes predictions.
Machine LearningTechnical Screen - OpenAIHardSoftware EngineerImplement a Contiguous Memory Allocator with Primitive Lists
Simulate best-fit allocation across a contiguous address range using only primitive lists and scalar state. Support splitting, exact-pointer frees, double-free rejection, deterministic tie-breaking, and coalescing adjacent free blocks across up to 10,000 operations.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerImplement a Distributed Rate Limiter
Implement a distributed token bucket rate limiter backed by a key-value store with optimistic concurrency control (CAS), handling clock skew, concurrent updates, and token replenishment.
Coding & AlgorithmsTechnical ScreenDistributed SystemsConcurrencyAlgorithms - 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 GPU credit manager
This question evaluates understanding of concurrent resource management, advanced data structures for top-K and per-user queries, enforcement of caps and expirations, and algorithmic complexity guarantees while maintaining atomicity under concurrent operations.
Coding & AlgorithmsTechnical Screen - 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 a memory allocator with malloc/free
This question evaluates understanding of memory allocator concepts including malloc/free semantics, contiguous allocation, fragmentation handling, coalescing of adjacent free blocks, pointer validation, and data-structure choices for efficient allocation.
Coding & AlgorithmsTechnical Screen - OpenAIHardSoftware EngineerImplement a minimal reverse-mode autograd engine on PyTorch tensors
Implement the core of a PyTorch-style autograd system: a tensor wrapper that records addition, multiplication, matrix multiplication, ReLU and sum, plus a backward method that fills in gradients for every input. Tests reverse-mode differentiation, correct ordering of the backward pass, gradient accumulation for tensors used more than once, and verification against PyTorch.
Machine LearningTechnical Screen - OpenAIMediumSoftware EngineerImplement a serializable key-value store
This question evaluates competency in implementing robust serialization and in-memory data structures, covering binary format design, handling arbitrary bytes and Unicode, correctness across edge cases (empty state, large keys/values, overwrites, deletions), input validation and failure recovery, complexity analysis, and unit testing.
Coding & AlgorithmsTechnical 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 - 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 - OpenAIMediumSoftware EngineerImplement an IPv4 Range Iterator
This problem tests your ability to manipulate 32-bit integers, understand bitwise operations, and implement a custom iterator for a contiguous range of IP addresses.
Coding & AlgorithmsTechnical ScreenBit ManipulationNetworkingIterator - OpenAIMediumSoftware EngineerImplement an expiring GPU credits ledger
This question evaluates understanding of time-based resource accounting, design of data structures for expiring balances, atomic update semantics for concurrent operations, and algorithmic time/space complexity within the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - 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 - OpenAIMediumSoftware EngineerImplement and Debug Backprop in NumPy
This question evaluates understanding of backpropagation and the chain rule, proficiency in vectorized NumPy implementation, numerical stability of softmax/cross-entropy, and competency in gradient checking and debugging of model gradients.
Machine LearningTechnical Screen - OpenAIMediumSoftware EngineerImplement delimiter-free string codec
This question evaluates a candidate's ability to design reversible string encodings that handle arbitrary characters and edge cases, testing competency in string manipulation, data serialization, and robustness.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerImplement expiring credit ledger
This question evaluates the ability to design efficient time-based data structures and algorithms for managing expiring credits with ordering and tie-breaking rules, testing competencies in event ordering, interval management, and retroactive update handling; it is in the Coding & Algorithms domain and emphasizes practical application of algorithmic and data-structure reasoning. It is commonly asked to verify correctness under out-of-order inserts and queries, to assess performance and complexity analysis for add/charge/get operations, and to require clear specification of time and space complexity for the proposed approach.
Coding & AlgorithmsTechnical Screen - OpenAIHardSoftware EngineerImplement follow graph with snapshots
This problem tests your ability to design a versioned, immutable, or persistent data structure that supports efficient graph modifications and point-in-time snapshot queries.
Coding & AlgorithmsTechnical ScreenPersistent Data StructuresGraphsVersion Control - OpenAIMediumSoftware EngineerImplement follow graph with snapshots and recommendations
This question evaluates design and implementation skills for mutable graph data structures with point-in-time snapshotting and recommendation ranking, testing knowledge of data structures, versioning, graph traversal, and algorithmic time/space complexity analysis.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerImplement in-memory DB querying
This question evaluates a candidate's competency in data structures, algorithms, and systems-level thinking for implementing query processing in an in-memory database, including projection, predicate filtering, ordering, and index design.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerImplement in-memory KV store with serialization
This question evaluates skills in designing and implementing an in-memory key-value store with serialization, testing data structure design, API design (set/get/serialize/deserialize), serialization format selection, type fidelity for common Python types, and robust error handling.
Coding & AlgorithmsTechnical Screen - 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 - 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 - OpenAIMediumSoftware EngineerImplement node messaging and path discovery
This question evaluates skills in distributed systems and algorithms, including reliable message-passing between adjacent nodes, graph traversal and path discovery, fault-tolerant protocol design, and message/time complexity analysis.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerImplement persistent key-value store
This question evaluates competency in implementing an in-memory key-value store with persistence, covering concepts such as serialization, durability, data structure management, and basic I/O handling.
Coding & AlgorithmsTechnical Screen - OpenAIHardSoftware EngineerImplement type AST and infer generics
This problem tests your ability to design a recursive data structure for an abstract syntax tree and implement a unification-based type inference engine for a simple functional language.
Coding & AlgorithmsTechnical ScreenASTType InferenceRecursion - 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
OpenAI