practice a little every day, paws crossed ♡
Coding & Algorithms 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
- Questions
- 546
- Companies
- 11
- Topics
- 8
- Languages
Showing 1021–1050 of 1706 results
- OpenAIHardSoftware EngineerCheapest Daily Shirt Colors With No Color Repeated on Consecutive Days
Pick a blue, green or red shirt for each of n days so that the total price is as low as possible while never buying the same color on two consecutive days, and return the chosen color sequence. It tests dynamic programming over a small state space and reconstruction of the optimal choices.
Coding & AlgorithmsTechnical Screen - OpenAIHardSoftware EngineerCheapest Paint-Booth Color Schedule With No Repeat on Consecutive Cars
Choose one of three paint colors for each car on an assembly line to minimize total cost, never repeating a color on consecutive cars, and return the exact color chosen for each car.
Coding & AlgorithmsTechnical Screendynamic-programmingreconstructiongreedy-vs-dp - OpenAIHardSoftware EngineerCompute Infection Time in a Grid
This problem tests your ability to model state propagation in a 2D grid using Breadth-First Search (BFS) to determine the time required for a dynamic condition to cover all reachable nodes.
Coding & AlgorithmsTechnical ScreenBFSGraphSimulation - OpenAIMediumSoftware EngineerCompute Plant Infection Stabilization
This problem tests your ability to simulate state propagation across a grid over discrete time steps and determine the minimum number of interventions required to contain an infection.
Coding & AlgorithmsTechnical ScreenSimulationGridBacktracking - OpenAIMediumSoftware EngineerCompute Plant Infection Time
This problem tests your ability to model a grid-based propagation process using Breadth-First Search (BFS), specifically handling multi-source initialization and obstacle avoidance.
Coding & AlgorithmsTechnical ScreenBFSGraphGrid - OpenAIMediumBackend EngineerConvert IPv4 Ranges to CIDR Blocks
This question evaluates understanding of IPv4 addressing, binary/bitwise manipulation, and the ability to summarize consecutive address ranges into minimal CIDR blocks, and belongs to the Coding & Algorithms domain for backend engineering roles.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerCount Connected Friend Groups
Determine the number of connected components in an undirected graph represented as an adjacency matrix using graph traversal or disjoint set union.
Coding & AlgorithmsTechnical Screengraphdfsbfs - OpenAIMediumMachine Learning EngineerDesign a Resumable Iterator with Checkpoint and Restore
This question evaluates a candidate's ability to design serializable, stateful abstractions in both in-memory and I/O-bound contexts. It tests understanding of iterator patterns, checkpoint-restore semantics, and test-driven development — competencies commonly assessed in engineering roles requiring systems thinking and API design rigor.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerDesign a persistent key-value store
This question evaluates a candidate's ability to design persistent storage and in-memory data structures, covering serialization of arbitrary values, medium/interface design for byte-level persistence, crash-consistent flushing, error handling, and performance and complexity analysis.
Coding & AlgorithmsTechnical Screen - OpenAIMediumMachine Learning EngineerDesign an Editable Text Buffer
This problem tests your ability to design an efficient data structure for text manipulation while implementing undo/redo history and a dynamic prefix-based autocomplete feature.
Coding & AlgorithmsTechnical ScreenData StructuresTrieUndo-Redo - OpenAIHardSoftware EngineerFollow One-Way Links to the Endpoint Node or the Last Node Before a Loop Closes
Given one-way links in which every node has at most one outgoing link, follow the links from a start node and return the endpoint where the walk stops, or the last node visited before the walk would revisit a node. Tests single-successor graph traversal, visited-node bookkeeping and loop edge cases.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerGenerate Data Labeling Schedules
This question evaluates combinatorial reasoning and constructive algorithm design for generating constrained assignment schedules, including ensuring each human appears a minimum number of times, preventing duplicate human-task pairs, and managing valid ID ranges.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerImplement A Contiguous Memory Allocator With Free-Block Coalescing
Design a fixed-size contiguous memory allocator supporting allocation and deallocation with immediate adjacent free-block coalescing.
Coding & AlgorithmsTechnical ScreenData StructuresIntervalsBinary Search - OpenAIEasySoftware EngineerImplement Chat Event Counter
This question evaluates data structures and algorithms competency, focusing on designing efficient in-memory counters and time-windowed event aggregation for (userId, chatId) pairs; it is categorized under Coding & Algorithms and has a practical implementation focus.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerImplement GPU credit ledger
This question evaluates a candidate's ability to design efficient stateful systems and algorithmic data structures for tracking per-tenant resource balances, including handling idempotency, negative balance policies, concurrency, and persistence.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerImplement IPv4 and CIDR iterators
This problem tests your ability to manipulate IP address bit-representations and implement a custom iterator to traverse all addresses within a given CIDR block.
Coding & AlgorithmsTechnical ScreenBitwiseNetworkingIterator - OpenAIMediumSoftware EngineerImplement KV store and plan type conversions
This question evaluates proficiency in designing scalable, time-versioned key-value data structures and in graph-based shortest-path planning for costed type conversions, assessing algorithmic thinking, complexity analysis, and robustness under large-scale constraints in the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerImplement KV store serialization
This question evaluates skills in binary serialization and deserialization, data encoding and layout, type tagging, endianness, checksumming, versioning for forward/backward compatibility, and algorithmic efficiency and space usage for an in-memory key-value store; it falls under the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - OpenAIMediumSoftware EngineerImplement Social Follow Recommendations
This problem tests your ability to navigate a social graph to implement a recommendation system using set operations and frequency counting.
Coding & AlgorithmsTechnical ScreenGraphHash MapSorting - OpenAIMediumSoftware EngineerImplement Social Graph Snapshot Queries
This problem tests your ability to design a query-optimized representation for a directed graph, specifically focusing on efficient retrieval of multi-hop relationships and neighbor-based ranking.
Coding & AlgorithmsTechnical ScreenGraphsAdjacency ListData Structures - OpenAIMediumSoftware EngineerImplement Time-Aware GPU Credit Ledger
Design an in-memory credit ledger that tracks GPU compute grants with expiration timestamps, consumes credits greedily by earliest expiration, and supports atomic deductions.
Coding & AlgorithmsTechnical ScreenHeap / Priority QueueDesignGreedy - 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 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 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 - 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 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 - 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
OpenAI