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 2041–2070 of 3276 results
- OktaMediumFrontend EngineerDeduplicate an Array in Linear Time
This question tests the ability to implement a deduplication algorithm that preserves the original relative order of elements while maintaining O(n) time and space complexity.
Coding & AlgorithmsTechnical ScreenArraysHash TableTime Complexity - OktaMediumSoftware EngineerValidate IPv4 Address List
This problem tests your ability to parse strings and apply conditional logic to validate technical data against specific constraints.
Coding & AlgorithmsTechnical ScreenStringsParsingValidation - OkxMediumSoftware EngineerGroup Strings By Anagram Signature
This problem tests your ability to normalize strings into canonical forms using hashing or frequency counting to identify anagrams efficiently.
Coding & AlgorithmsTechnical ScreenHash MapStringsAnagrams - OmnissaMediumSoftware EngineerAlternate Odd and Even Numbers with Two Threads
This problem tests knowledge of thread synchronization using locks and condition variables to enforce a specific execution order between two concurrent processes.
Coding & AlgorithmsOnsiteConcurrencyMultithreadingSynchronization - OmnissaMediumSoftware EngineerCheck Whether a Singly Linked List Is a Palindrome
Tests the ability to determine if a singly linked list is a palindrome in O(n) time and O(1) auxiliary space using two pointers and in-place list reversal.
Coding & AlgorithmsOnsiteLinked ListTwo PointersIn-Place Reversal - OmnissaMediumSoftware EngineerFind the Celebrity from a Knows Matrix
This problem tests the ability to solve a search problem in O(N) time by utilizing the transitive and exclusionary properties of the 'knows' relationship to eliminate candidates.
Coding & AlgorithmsOnsiteArraysTwo PointersAlgorithms - OmnissaMediumSoftware EngineerFind the Maximum Sum of a Contiguous Subarray
This problem tests the ability to implement Kadane's algorithm to find the maximum sum of a contiguous subarray, specifically focusing on handling negative integers and maintaining optimal time and space complexity.
Coding & AlgorithmsOnsiteArraysDynamic ProgrammingKadane's Algorithm - OmnissaMediumSoftware EngineerRepeatedly Remove Adjacent Equal Characters
This problem tests your ability to handle recursive reduction patterns in a string using a stack-based approach to achieve linear time complexity.
Coding & AlgorithmsOnsiteStackStringGreedy - OnepayEasySoftware EngineerCount Complete Highway Journeys from Toll Logs
This problem tests string manipulation, hash map usage, and state tracking to identify valid entry-to-exit sequences from an unordered stream of toll logs.
Coding & AlgorithmsTechnical ScreenHash MapsSortingData Streams - OpenAIMediumSoftware EngineerAdd Consecutive-Value Bonuses to Grid Paths
Tests dynamic programming on a 2D grid with extended state tracking to incorporate multi-step path history for score bonuses, path counting, and lexicographical path reconstruction.
Coding & AlgorithmsOnsitedynamic-programminggridpathfinding - OpenAIHardSoftware EngineerAggregate Recent Message Events And Active Chats
Design an in-memory aggregation system that tracks rolling window message counts and distinct active entities across chats with bounded memory and O(1) amortized operations.
Coding & AlgorithmsOnsiteSliding WindowData StreamsDesign - OpenAIMediumAndroid EngineerBuild a Compose Rating Card
Tests proficiency in modern Android development with Kotlin and Jetpack Compose, focusing on unidirectional data flow (UDF), custom stateless composables, ViewModel state management, and asynchronous submission handling.
Coding & AlgorithmsTechnical Screenandroidjetpack-composekotlin - OpenAIMediumFrontend EngineerBuild a Streaming Chat Input
This question evaluates frontend engineering skills including streaming data handling, incremental token-by-token rendering, asynchronous state management, and preserving UI responsiveness during long-running API streams.
Coding & AlgorithmsTechnical Screen - 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 - OpenAIMediumSoftware EngineerCompute infection spread time
This problem tests your ability to model a spreading process on a 2D grid using a multi-source Breadth-First Search (BFS) to determine the time required for a state to propagate across the entire space.
Coding & AlgorithmsOnsiteBFSGraphsGrid - 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 - OpenAIHardSoftware EngineerCount Ordered Four-Shop Road Paths That Visit One Shop of Each Type
Count the ordered routes through a town's road network that visit exactly one shop of each of four types, where consecutive shops must share a direct road and a route and its reverse count separately. Tests graph modeling, path enumeration under type constraints and careful counting on small graphs.
Coding & AlgorithmsOnline Assessment - 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 parser for a hypothetical language
This question evaluates competency in compiler and language design, covering grammar analysis, parsing algorithms (LL/LR/GLR/Earley/PEG), lexer and parser implementation, AST construction, error reporting and recovery, operator precedence and associativity, and analysis of time/space trade-offs.
Coding & AlgorithmsOnsite - 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 - OpenAIMediumMachine Learning EngineerFind Minimum Compatible Version
Implement an algorithm to find the earliest compatible software version while minimizing expensive compatibility-check API calls across partitioned version branches.
Coding & AlgorithmsOnsiteBinary SearchAlgorithmsOptimization - OpenAIMediumMachine Learning EngineerFind the First Working Version
This question tests the ability to combine custom comparison logic with a binary search approach to identify the first transition point in a monotonic sequence.
Coding & AlgorithmsOnsiteBinary SearchAlgorithmsOptimization - 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
Okta
OpenAI