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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
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Showing 1321–1350 of 3276 results
- HarveyMediumMachine Learning EngineerImplement a Spreadsheet With Formulas
This problem tests your ability to model cell dependencies using a directed graph, handle topological sorting for re-evaluation, and identify circular references.
Coding & AlgorithmsTechnical ScreenGraphsRecursionDFS - HarveyMediumSoftware EngineerImplement an Integer Spreadsheet with Formulas
Design an in-memory integer spreadsheet supporting cell assignments, additive formulas with nested references, and dynamic recalculation of acyclic dependency chains.
Coding & AlgorithmsTechnical ScreenDesignGraphDFS - HarveyMediumBackend EngineerImplement tag matcher and filesystem
This combined prompt evaluates string-processing and parsing skills for tag matching and design/implementation skills for an in-memory file system, measuring competencies in exact whole-word matching, case normalization, punctuation and duplicate handling, path parsing, hierarchical data structures, and file API behaviors.
Coding & AlgorithmsOnsite - HarveyMediumSoftware EngineerIn-Memory File System: Create, Track Duplicates, and List
Design an in-memory file system supporting directory creation, file creation with automated duplicate-name collision resolution, content retrieval, and directory listing.
Coding & AlgorithmsOnsiteTrieDesignTree - HarveyMediumSoftware EngineerSpreadsheet Formula Engine with Cycle Detection
Design an in-memory spreadsheet formula engine supporting cell assignments, formula evaluation with dependencies, and cycle detection. The question tests directed graph modeling, topological invalidation, and cycle detection algorithms.
Coding & AlgorithmsTechnical Screengraphcycle-detectiontopological-sort - HeadwayMediumSoftware EngineerDebug and extend obstacle-run statistics classes
This question evaluates object-oriented design, debugging, algorithmic reasoning, and probabilistic simulation competencies by requiring fixes to class behavior, implementation of aggregate statistics, and a Monte Carlo-based probability estimator.
Coding & AlgorithmsTechnical Screen - HeadwayMediumSoftware EngineerGenerate Every Letter String a Phone Keypad Digit Sequence Can Spell
Given a string of digits from 2 to 9, return every letter string those digits can spell on a standard phone keypad, in lexicographic order. It tests systematic enumeration of combinations, keys that carry four letters, and producing a deterministic output order.
Coding & AlgorithmsTechnical Screen - HeadwayHardSoftware EngineerImplement Journey Counter and Speeder Detector
This problem tests your ability to process time-series event data by grouping related actions, managing state across sequences, and performing geometric or threshold-based calculations.
Coding & AlgorithmsTechnical ScreenHash MapsTime-SeriesState Management - HebbiaHardSoftware EngineerDetect a Winner on a 3x3 Tic-Tac-Toe Board
This problem tests your ability to efficiently represent board states and implement win-condition logic for a grid-based game.
Coding & AlgorithmsOnsiteArraysLogicGames - HebbiaMediumSoftware EngineerImplement Ultimate Tic-Tac-Toe
This problem tests your ability to design a state-management system for a nested game board and implement recursive winner-detection logic.
Coding & AlgorithmsTechnical ScreenOODState ManagementGame Theory - HebbiaMediumSoftware EngineerImplement a Cache Snapshot Printer
This question evaluates understanding of LRU cache semantics, data structures for maintaining recency and eviction, and techniques for serializing or compressing state by grouping identical values while preserving ordering.
Coding & AlgorithmsOnsite - Hive.AiHardSoftware EngineerDetect a Reachable Negative Cycle
This problem tests the implementation of the Bellman-Ford algorithm to identify negative cycles reachable from a source vertex, specifically requiring careful handling of unreachable nodes to avoid incorrect cycle detection.
Coding & AlgorithmsTechnical ScreenGraphsShortest-PathBellman-Ford - Hive.AiHardSoftware EngineerMeasure Water Trapped Between Elevations
This problem tests the ability to solve a classic dynamic programming/two-pointer challenge by calculating the volume of trapped water between bars of varying heights.
Coding & AlgorithmsTechnical ScreenArraysTwo PointersDynamic Programming - Hive.AiHardSoftware EngineerTrack the Median of a Stream
This problem tests your ability to maintain sorted order in a streaming context using balanced data structures to achieve optimal time complexity for insertions and median retrieval.
Coding & AlgorithmsTechnical ScreenHeapsData StructuresStreaming Algorithms - Hive.AiHardSoftware EngineerValidate Adding an Edge to a Directed Acyclic Graph
This problem tests your ability to manipulate graph structures and implement reachability checks, specifically ensuring that adding an edge to a Directed Acyclic Graph (DAG) maintains its acyclic property.
Coding & AlgorithmsTechnical ScreenGraphsDAGDFS/BFS - HouzzMediumSoftware EngineerConvert a Column Number to an Excel-Style Label
Convert one-based spreadsheet columns into A-through-Z and AA-through-ZZ labels, with correct handling of multiples of 26.
Coding & AlgorithmsOnline Assessment - HubSpotMediumSoftware EngineerDesign a bank with scheduled payments and merges
This question evaluates data-structure and algorithm design competencies with emphasis on concurrency, time-based scheduling, aggregation (TopK), transactional consistency, idempotency, and merge semantics for an in-memory banking service, falling under the Coding & Algorithms and system-design domain.
Coding & AlgorithmsOnline Assessment - HubSpotMediumSoftware EngineerDesign and implement a bank account system
This question evaluates a candidate's skills in system design, data modeling, transactional integrity, concurrency control, idempotency, API design, and algorithmic complexity for implementing a minimal banking service.
Coding & AlgorithmsOnline Assessment - HubSpotEasySoftware EngineerFind a special person using knows(a,b)
This question evaluates algorithmic reasoning about pairwise relation inference using an oracle-style knows(a, b) API and the ability to minimize API calls, testing skills in graph modeling and asymptotic analysis.
Coding & AlgorithmsOnsite - HubSpotMediumSoftware EngineerFind spammer with minimal hasMessaged calls
Find the "spammer" account that messaged every other account but received from none, using only a hasMessaged(a, b) oracle. This is the classic find-the-celebrity problem inverted, solved with a two-phase elimination-then-verify algorithm in O(n) oracle calls and O(1) extra space, with full correctness proof and edge-case handling.
Coding & AlgorithmsOnsite - HubSpotMediumSoftware EngineerImplement account CRUD and transfer
This interview question evaluates requirements, scale assumptions, API/data design, architecture, trade-offs, failure modes, and rollout in a realistic interview setting. A strong answer for Implement account CRUD and transfer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsOnline Assessment - HubSpotMediumSoftware EngineerValidate hiring request under role constraints
This problem tests your ability to manage state mapping and validate cardinality constraints using hash maps, requiring efficient lookups to ensure hiring requests remain within predefined role limits.
Coding & AlgorithmsTechnical ScreenHash MapsData ValidationState Management - Hudson River TradingMediumSoftware EngineerApproach verbose data-structure design
This question evaluates a candidate's ability to design and implement complex data structures, testing algorithmic reasoning, time/space complexity analysis, state modeling, and organization of code and tests.
Coding & AlgorithmsTechnical Screen - Hudson River TradingEasySoftware EngineerBall Position in a Tilting Maze After Timed Tilt Events
Live coding simulation problem: a ball sits in a grid maze on a board that can tilt up, down, left or right or lie flat, and timed events change the tilt. Return the ball's cell at an end time that can be very large. It tests precise timing rules, wall handling and movement code that scales to long time spans.
Coding & AlgorithmsTechnical Screen - Hudson River TradingMediumSoftware EngineerCalculate Completion Time for a Single-Server Reactor Queue
Simulate a single-threaded reactor queue with a bounded buffer to compute the completion timestamp or drop status for each incoming task.
Coding & AlgorithmsTechnical ScreenQueueSimulationArrays - Hudson River TradingEasySoftware EngineerCheck Root-To-Leaf Target Sums In A Binary Tree
This question tests your ability to traverse a binary tree using depth-first search (DFS) or breadth-first search (BFS) while tracking path accumulators and accurately identifying valid leaf nodes.
Coding & AlgorithmsTechnical ScreenBinary TreeDFSRecursion - Hudson River TradingMediumSoftware EngineerCount Digit-Reversal Equivalent Pairs
Count pairs of indices in an integer array whose values share the same canonical digit-reversal form.
Coding & AlgorithmsTechnical ScreenHash TableMathString - Hudson River TradingMediumSoftware EngineerCount Length-3 Chat Substrings with a Vowel
Count the number of distinct length-3 alphabetical substrings in a chat message that contain at least one vowel.
Coding & AlgorithmsTechnical Screenstringsliding-windowhash-set - Hudson River TradingEasyMachine Learning EngineerCount People Reaching the Boundary
This question evaluates algorithmic simulation and event-driven modeling skills, specifically handling discrete versus continuous time, visibility constraints relative to a stationary watcher that changes facing direction, and boundary conditions for state transitions.
Coding & AlgorithmsOnsite - Hudson River TradingMediumData ScientistCount Smaller Numbers with Only Zero and One in Base Four
Count the number of positive integers strictly less than n whose base-4 representation consists only of the digits 0 and 1.
Coding & AlgorithmsOnline AssessmentMathBit ManipulationDigit DP
Harvey
HubSpot
Hudson River Trading