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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.
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Showing 2011–2040 of 3276 results
- NextdoorMediumMachine Learning EngineerBuild Ranked Feed With Photo Batching
This question evaluates algorithmic reasoning and data manipulation skills, including stable sorting, grouping/batching, and merging of ranked items while preserving ordering invariants.
Coding & AlgorithmsTechnical Screen - NextdoorEasyiOS EngineerFlatten Nested Comments
This problem tests your ability to traverse a nested tree structure (comments) and flatten it into a linear representation while respecting hierarchical depth levels.
Coding & AlgorithmsTechnical ScreenTreesRecursionData Structures - 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 - 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 - NielsenMediumSoftware EngineerPrefix Tree Supporting Insert, Exact Search and Prefix Queries
A coding problem that processes a sequence of insert, exact-match search and prefix-check operations on lowercase words and returns the boolean answers to the queries in order. It tests building a character-level word index and correctly separating whole-word matches from words that are only prefixes of others.
Coding & AlgorithmsOther - 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 - NooksMediumSoftware EngineerImplement a BFS web crawler
This question evaluates proficiency in breadth-first search and graph traversal concepts applied to web crawling, including handling duplicate links, hostname filtering, and tracking visited URLs.
Coding & AlgorithmsOnsite - 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 EngineerFind Top Errors in Time Window
This problem tests your ability to process streaming log data within a sliding time window, aggregate frequencies using hash maps, and implement custom sorting logic.
Coding & AlgorithmsOnsiteHash MapSortingData Processing - 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 - 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 - NuroMediumSoftware EngineerFind Intersections Between Two Interval Lists
This problem tests your ability to efficiently merge and find overlaps between two sorted interval lists using a two-pointer approach.
Coding & AlgorithmsTechnical ScreenTwo PointersIntervalsSorting - NuroHardMachine Learning EngineerFind Maximum Path Sum in N-ary Tree
This question evaluates understanding of tree traversal and aggregation techniques, including handling of variable-arity nodes, negative values, and path-based dynamic programming on N-ary trees.
Coding & AlgorithmsTechnical Screen - NuroMediumSoftware EngineerFind gaps between intervals
This question evaluates interval manipulation and range-coverage reasoning, testing skills in sorting, merging overlapping ranges, and handling boundary conditions within the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - NuroMediumSoftware EngineerGenerate Weighted Random Keys With Add And Remove
This problem tests your ability to efficiently manage a collection of weighted items and perform random sampling based on those weights, requiring O(log N) updates and lookups.
Coding & AlgorithmsTechnical ScreenData StructuresPrefix SumBinary Search - NuroMediumSoftware EngineerGroup points by distance threshold
This problem tests your ability to efficiently group spatial points based on proximity using graph traversal or clustering techniques while managing computational complexity.
Coding & AlgorithmsTechnical ScreenGraphsGeometryDSU - NuroHardBackend EngineerImplement BFS and a Job Scheduler
Solve grid reveal with BFS and design a thread-safe periodic job scheduler. The solution covers Minesweeper-style expansion, queue processing, priority-queue scheduling, locks, worker pools, cancellation, duplicate prevention, long-running tasks, clock drift, and backpressure.
Coding & AlgorithmsOnsite - NuroMediumSoftware EngineerMap Weighted Random Draws to Indices
This problem tests your ability to efficiently map a series of random draws to specific indices based on provided weights using binary search techniques.
Coding & AlgorithmsTechnical ScreenArraysBinary SearchPrefix Sum - NuroMediumSoftware EngineerMaximize Revenue With Two Contiguous Delivery Routes
This problem tests dynamic programming and prefix-max techniques to find the maximum revenue of two non-overlapping subarrays with given length constraints.
Coding & AlgorithmsTechnical ScreenDynamic ProgrammingSliding WindowPrefix Sums - NuroMediumSoftware EngineerPick Two Trees for a Zipline That Maximizes Height Times Span
A coding question that recasts the classic two-line container problem as choosing two trees in a row to string a zipline between. It asks for the largest value of the shorter tree's height times the distance between the two trees, over arrays of up to 100,000 heights, and tests efficient pair selection.
Coding & AlgorithmsTechnical Screen - NuroMediumSoftware EngineerReveal a Minesweeper Board
This problem tests recursive graph traversal (DFS/BFS) and grid manipulation logic to implement the recursive uncovering mechanism found in Minesweeper.
Coding & AlgorithmsTechnical ScreenDFSRecursion2D-Grid - NuroHardSoftware EngineerReveal a Minesweeper Region with Adjacent-Mine Counts
Implement a Minesweeper cell-reveal algorithm that dynamically calculates 8-directional mine adjacencies and expands blank regions while safely avoiding recursion depth pitfalls on large boards.
Coding & AlgorithmsTechnical Screenbfsdfsmatrix - NutanixHardSoftware EngineerFind Peak Memory Usage Across Process Intervals
Calculate the peak simultaneous memory usage from a set of half-open intervals and identify the earliest continuous time window sustaining that peak.
Coding & AlgorithmsTechnical Screensweep-lineintervalsprefix-sum - NutanixHardSoftware EngineerFind the Most Reliable Path Through a Network
Implement an algorithm to find the maximum end-to-end success probability between two nodes in an undirected network with multiplicative edge probabilities. Tests graph traversal, Dijkstra's algorithm variant with max-heaps, and edge-case handling.
Coding & AlgorithmsTechnical ScreenGraphDijkstraHeap
Nextdoor
Nielsen
Notion
Nuro