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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 2821–2850 of 4616 results
- NextdoorMediumSoftware EngineerGroup Photos and Sort Feed Items
Implement a feed transformation that collapses consecutive photo posts by the same user into album items and then stably sorts the resulting feed by timestamp.
Coding & AlgorithmsTechnical ScreenArraysSortingTwo Pointers - NextdoorMediumMachine Learning EngineerImplement ordering with dependency constraints
This question evaluates understanding of dependency resolution and ordering within graph-based problems, including cycle detection, lexicographic tie-breaking, and extensions requiring certain items to appear as contiguous groups.
Coding & AlgorithmsTechnical Screen - NextdoorMediumSoftware EngineerImplement version string comparator with extensions
This question evaluates string parsing and comparison algorithms, handling of numeric versus lexical ordering and versioning semantics (including pre-release identifiers and ignored build metadata), within the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - NextdoorMediumData ScientistMeasure Local News Launch Success
This problem tests your ability to design an experimentation framework for a localized product launch and identify potential confounding factors and interference effects.
Analytics & ExperimentationTechnical ScreenExperimentationCausal InferenceMetrics - NextdoorMediumMachine Learning EngineerMerge overlapping weekly time intervals
This question evaluates the ability to parse weekday and 24-hour time strings, reason about interval overlap, and apply efficient merging and sorting techniques for time-based intervals.
Coding & AlgorithmsTechnical Screen - NextdoorHardSoftware EngineerSimulate Transaction Lock Scheduling
Implement an in-memory lock manager simulating shared and exclusive lock scheduling with strict FIFO queuing to prevent starvation.
Coding & AlgorithmsTechnical ScreenConcurrencyDesignQueue - NextdoorHardData EngineerWrite SQL for app metrics
This question evaluates proficiency in SQL-based data engineering, focusing on time-zone-aware timestamp handling, aggregation of event and relationship data, cohort retention analysis, and computation of product metrics like DAU, new users, photo activity, and follower distributions.
Coding & AlgorithmsTechnical Screen - NextdoorHardData EngineerWrite SQL for basic user metrics
This question evaluates proficiency in SQL for relational databases, specifically testing aggregation, joins, date/time grouping, and handling tied results when computing user metrics such as total users, peak signup month, and top-followed users.
Coding & AlgorithmsTechnical Screen - NgrokMediumSoftware EngineerGenerate Color Feedback for a Word Guess
Generate green, yellow, or red feedback for each character in a word guess based on positional equality and presence anywhere in the answer. Follow the stated presence semantics, where misplaced duplicate letters remain yellow rather than consuming a limited match count.
Coding & AlgorithmsTechnical Screen - NgrokMediumSoftware EngineerSupport String Membership and Random Sampling
Design an immutable in-memory string collection with exact membership checks and uniform random sampling over stored values. Combine complementary indexing and positional storage, analyze time and memory, and compare the approach with a trie for prefix sharing and future mutations.
Software Engineering FundamentalsTechnical Screen - NielsenMediumBackend EngineerDesign a Train Ticket Booking System
This problem evaluates your ability to design a robust reservation system that handles concurrent bookings, maintains data integrity, and adheres to clean object-oriented design principles.
Software Engineering FundamentalsTechnical ScreenConcurrencySystem DesignDatabase - NikeMediumSoftware EngineerChoose a Sorting Algorithm from Workload Constraints
Tests your ability to evaluate classical sorting algorithms against concrete workload constraints such as memory access patterns, worst-case guarantees, stability, and streaming limits.
Software Engineering FundamentalsTechnical ScreenSortingAlgorithmsData Structures - NikeMediumSoftware EngineerDesign a PDF Ingestion and Retrieval-Augmented Generation Pipeline
This problem tests the ability to design an end-to-end RAG pipeline capable of handling complex document parsing, chunking strategies for citations, and efficient synchronization of updates.
ML System DesignTechnical ScreenRAGPDF ParsingVector Databases - NikeMediumSoftware EngineerWrite Pseudocode for Embedding Creation and Vector Search
This problem tests the ability to design a robust production pipeline for generating text embeddings and performing efficient, metadata-aware vector retrieval.
Machine LearningTechnical ScreenEmbeddingsVector DBData Pipelines - NioMediumSoftware EngineerFind kth smallest and count stair-climbing ways
This problem tests your ability to implement an efficient selection algorithm for order statistics and a dynamic programming approach to solve a classic combinatorial staircase problem.
Coding & AlgorithmsTechnical ScreenQuickSelectDynamic ProgrammingAlgorithms - NordstromMediumSoftware EngineerSenior Engineer Leadership Screen: Project Scope, Coding Time, Ownership, Hard Problems
This interview scenario assesses senior-level engineering leadership, architectural ownership, and the practical balance between hands-on coding and technical coordination within high-throughput systems like fulfillment and supply chain.
Behavioral & LeadershipTechnical Screenleadershipbehavioralsystem-ownership - NotionMediumData ScientistAnalyze Document Collaboration CSVs
This problem tests your ability to clean, join, and analyze messy user-activity data using pandas or SQL, focusing on window functions and handling missing values.
Data Manipulation (SQL/Python)Technical ScreenSQLPandasData Cleaning - NotionEasyData ScientistAnalyze document collaboration from CSV logs
This question evaluates data manipulation and analytical competencies—particularly deduplication, joins, aggregation, co-occurrence counting, and metric definition—applied to CSV access logs and user metadata.
Data Manipulation (SQL/Python)Technical Screen - NotionMediumData ScientistAnalyze document collaboration patterns
This question evaluates a candidate's competency in data manipulation and analytics—specifically joins, deduplication of user-document pairs, aggregation, and computation of user- and country-level collaboration metrics using SQL or Python.
Data Manipulation (SQL/Python)Technical Screen - NotionMediumSoftware EngineerDesign a text editor with undo/redo
This question evaluates understanding of stateful data structures, operation/command semantics for reversible actions, undo/redo stack management, interface design, complexity analysis, and test coverage for mutable editors.
Coding & AlgorithmsTechnical Screen - NotionMediumSoftware EngineerImplement Recursive React JSON Viewer with Collapse
Implement Recursive React JSON Viewer with Collapse evaluates requirements, assumptions, structured reasoning, trade-offs, and verification in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Software Engineering FundamentalsTechnical Screen - NubankMediumSoftware EngineerDesign an Online Coding Competition Platform
Design a scalable online coding contest platform capable of securely executing untrusted user code, producing deterministic scores, and maintaining both a real-time top-100 leaderboard and exact rank lookups.
System DesignTechnical ScreenDistributed SystemsLeaderboardsSecurity - NuroMediumSoftware EngineerAssign Robots to Nearest Pickup Items on a Grid with Obstacles
Given a grid with blocked cells, k delivery robots and k pickup items, assign every robot exactly one item by repeatedly matching the closest remaining robot-item pair under fixed tie-breaking rules. It tests shortest-path distances on grids with obstacles and careful, deterministic greedy assignment.
Coding & AlgorithmsTechnical Screen - NuroMediumSoftware EngineerBuild a Concurrent Recurring Job Scheduler
This problem tests your ability to design a thread-safe, concurrent task scheduling system that manages recurring executions while handling lifecycle events like cancellation and graceful shutdown.
Software Engineering FundamentalsTechnical ScreenConcurrencyMultithreadingDesign Patterns - NuroHardSoftware EngineerBuild a Thread-Safe Video Playback Loop at 25 FPS
Design and implement a thread-safe video playback engine that decodes and renders frames at a steady 25 frames per second using bounded buffering and precise monotonic scheduling.
Software Engineering FundamentalsTechnical ScreenConcurrencyMultithreadingSystems Design - NuroHardSoftware EngineerC++ K-Way Merge of Timestamped Records with Clean Class Design and Hand-Written Tests
Merge k input sequences of timestamped records, each already sorted by timestamp, into one ordered sequence in C++. The exercise stresses defining the record type, the merging class's state and interface, deterministic handling of equal timestamps, and writing your own C++ test cases without a judge harness.
Software Engineering FundamentalsTechnical Screen - NuroHardSoftware EngineerCheck Vertical Reflection Symmetry with Duplicate Points
Determine whether a multiset of 2D points is symmetric across a vertical line, preserving duplicate counts and allowing half-integer axes.
Coding & AlgorithmsTechnical Screen - NuroEasyData EngineerCompute unique duration by merging intervals
This question evaluates a data engineer's proficiency in temporal data manipulation and interval-set reasoning using SQL and Python, specifically skills in merging overlapping intervals and computing deduplicated cumulative durations.
Data Manipulation (SQL/Python)Technical Screen - NuroHardSoftware EngineerCoordinate Video Reading and Rendering at 25 Frames per Second
Design a 25fps video player with serialized unsafe APIs, bounded producer-consumer buffering, deadline pacing, and explicit timing feasibility limits.
Software Engineering FundamentalsTechnical Screen - NuroMediumSoftware EngineerDesign a Reliable Job Scheduler
Design a fault-tolerant distributed job scheduler capable of handling delayed execution, job cancellation, timeout detection, and automatic worker retries.
System DesignTechnical ScreenDistributed SystemsJob SchedulerFault Tolerance
Nextdoor
Nielsen
Notion
Nuro