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Software Engineer 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 151–180 of 520 results
- Capital OneMediumSoftware EngineerSorted Sums of Absolute Differences Over All Cyclic Shifts of an Array
Given two integer arrays of equal length, compute the sum of absolute differences between the second array and every cyclic rotation of the first, then return all of these sums in non-descending order. It tests rotation index arithmetic, accumulation over every shift, and exact output ordering.
Coding & AlgorithmsOnline Assessment - Capital OneHardSoftware EngineerSum of Distinct Values on the Borders of All Maximum-Sum Square Frames
Among all square frames of a given size inside an integer matrix, find those with the largest border sum, then add up the distinct values that appear on the borders of every such frame. Tests careful border enumeration that excludes interior cells, tie handling across several frames, and de-duplication by value.
Coding & AlgorithmsOnline Assessment - Chicago Trading CompanyEasySoftware EngineerMerge Nested Dictionaries Iteratively
This question evaluates a candidate's skill in iterative data structure manipulation and handling of nested dictionary merging semantics, including conflict resolution and value overriding.
Coding & AlgorithmsOnline Assessment - CircleMediumSoftware EngineerDescribe pair-programming challenge under time pressure
Describe pair-programming challenge under time pressure evaluates behavioral evidence, ownership, communication, trade-offs, and measurable outcomes in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Behavioral & LeadershipOnline Assessment - CircleHardSoftware EngineerDesign banking payment scheduling system
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 Design banking payment scheduling system states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
System DesignOnline Assessment - CircleHardSoftware EngineerDesign flight-price search service
Design flight-price search service evaluates requirements, scale assumptions, API/data design, architecture, trade-offs, failure modes, and rollout in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
System DesignOnline Assessment - CircleHardSoftware EngineerDesign in-memory DB with TTL and backup
A Circle software-engineer take-home: design a versioned in-memory key→(field→value) database with per-field TTL, append-only history and delete tombstones, lexicographically ordered scan and scanPrefix (correct even with special characters), and snapshot backup/restore counters. It exercises data modeling, time-travel visibility semantics, ordered indexing, garbage collection, and per-operation complexity trade-offs.
System DesignOnline Assessment - CircleMediumSoftware EngineerImplement a simplified multi-level banking system
Implement a simplified multi-level banking system evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsOnline Assessment - CircleMediumSoftware EngineerImplement cheapest itinerary with date filters
This question evaluates proficiency in graph algorithms and constrained pathfinding, including handling date filters for initial departures, time-ordered connections, cycle avoidance, and quantitative complexity analysis.
Coding & AlgorithmsOnline Assessment - CircleMediumSoftware EngineerTrace and reduce redundant curl requests
A practical curl interview question on tracing and reducing redundant HTTP requests: instrumenting a curl-based client, finding duplicate calls, and cutting request volume. Includes a full worked solution.
System DesignOnline Assessment - CircleMediumSoftware EngineerWrite PostgreSQL updates with date filters
This question evaluates competency in PostgreSQL data manipulation, covering updates with correct timestamp handling, upserts with conflict resolution, date-range selection using timestamptz, and index design plus performance analysis with EXPLAIN ANALYZE.
Data Manipulation (SQL/Python)Online Assessment - CiscoMediumSoftware EngineerSolve max-subarray, min-unique, and grid-jump
This question evaluates array algorithms and algorithmic problem-solving skills, specifically contiguous-sum optimization (greedy/DP reasoning), frequency counting and memory-constrained selection for unique minima, and grid traversal simulation with boundary and visit-state management.
Coding & AlgorithmsOnline Assessment - CitadelHardSoftware EngineerBuild models for housing and wind power prediction
This question evaluates ML system design and applied modeling competencies, including data assumptions, preprocessing, feature engineering, model selection, validation strategies, temporal leakage handling, and end-to-end pipeline construction for a binary housing-affordability classifier and a time-series regression for wind-farm power prediction.
ML System DesignOnline Assessment - CitadelMediumSoftware EngineerCompute max team size with a core interval
This question evaluates algorithmic problem-solving around interval overlap and time-complexity optimization, measuring the ability to determine the maximum team size given a core interval while reasoning about interval intersections and scalability; it is commonly asked to assess correctness and subquadratic runtime thinking, categorized under Coding & Algorithms and emphasizing practical algorithmic implementation. The follow-up evaluates combinatorics and counting under adjacency constraints with modular arithmetic and efficient handling of large parameters, commonly posed to test recurrence reasoning and scalable counting approaches, falling under combinatorics/dynamic programming and emphasizing conceptual understanding linked to practical algorithmic efficiency.
Coding & AlgorithmsOnline Assessment - CitadelMediumSoftware EngineerCompute maximum later-earlier difference
This problem tests your ability to optimize an O(n^2) brute-force search into an O(n) linear-time solution using a single-pass scan while maintaining state variables.
Coding & AlgorithmsOnline AssessmentArraysOptimizationGreedy - CitadelHardSoftware EngineerEvery MEX Reachable With At Most One Bounded Increment
A coding problem about memory blocks with values below n: using at most one increment of a single value, never raising a value to n, list every minimum excluded value (MEX) the array can end up with. It tests careful case analysis of how one increment can open or fill a gap, handling duplicate values, and returning the sorted answer efficiently.
Coding & AlgorithmsOnline Assessment - CitadelHardSoftware EngineerEvery Reachable Priority Gap After At Most One Bounded Bump
Given n network ports each tagged with a priority code below n, find every value the lowest unused priority code could take after at most one bounded increment. Tests careful case analysis of how a single bump opens or closes a gap, and returning the answer efficiently.
Coding & AlgorithmsOnline Assessmentarrayscountingmex - CitadelHardSoftware EngineerFirst Free Locker Number After One Tag Bump
Given locker tags in [0, n-1], list every possible smallest missing tag after at most one capped +1 adjustment. Tests MEX reasoning, careful case analysis around duplicates, and an O(n) solution.
Coding & AlgorithmsOnline Assessmentarrayscountingcase-analysis - CitadelMediumSoftware EngineerMinimize changes for k-periodic palindrome
This question evaluates understanding of string algorithms and combinatorial reasoning, focusing on palindrome properties combined with k-periodicity and the ability to minimize character changes under global constraints.
Coding & AlgorithmsOnline Assessment - CitadelMediumSoftware EngineerMinimize image processing cost with discount
This question evaluates a candidate's competence in algorithm design and optimization, including interval-based cost aggregation and modular arithmetic for large-number results within the Coding & Algorithms domain.
Coding & AlgorithmsOnline Assessment - CitadelMediumSoftware EngineerRefactor a Correct but Quadratic C++ Routine Under a Microsecond Budget
Optimize an inefficient, quadratic tree-resolution routine into a linear-time, cache-friendly implementation suitable for ultra-low-latency execution.
Software Engineering FundamentalsOnline AssessmentTreePerformance OptimizationGraph Traversal - CodeiumMediumSoftware EngineerFind the third-largest word by length
This question evaluates proficiency in string and array manipulation, ordering by key metrics (string length), and handling tie-breaking via stable ordering, situated in the Coding & Algorithms domain.
Coding & AlgorithmsOnline Assessment - CoinbaseMediumSoftware EngineerBuild Task Management Through Records, Search, Assignment, and Completion
Implement an in-memory task management system that tracks task lifecycles, assignments, and deadlines with efficient indexing and querying. Tests data structure design, state management, and multi-field sorting.
Software Engineering FundamentalsOnline Assessmentdata-structureshash-tablesorting - CoinbaseEasySoftware EngineerClarify CodeSignal partial credit and score access
This question evaluates understanding of how multi-level coding assessments allocate partial credit for test cases and compute aggregate scores across levels on an online assessment platform, testing competency in assessment logistics and test platform mechanics.
Behavioral & LeadershipOnline Assessment - CoinbaseHardSoftware EngineerDesign a Timestamped Cloud Credit Ledger with Rebates, Merges, and History
Design an in-memory cloud credit ledger that processes top-ups, charges with delayed deterministic rebates, account merges with canonical alias resolution, historical balance lookups, and spending leaderboards.
Software Engineering FundamentalsOnline AssessmentData StructuresDesignHeap - CoinbaseHardSoftware EngineerDesign a bank account ledger
A complete take-home system-design walkthrough for a bank account ledger service: APIs and data model, an immutable double-entry ledger for auditability, ACID single-account updates and atomic multi-account transfers, idempotency and exactly-once effects, concurrency control, real-time/as-of/historical balance reads, monthly statements, reconciliation with external payment rails, limits, fraud and dispute handling, plus sharding, replicas, recovery, and monitoring strategies for scale.
System DesignOnline Assessment - CoinbaseMediumSoftware EngineerDesign a task management system with TTL
This question evaluates the ability to design in-memory data models and algorithms for time-based task assignment semantics, including TTL-based expiration, per-user quotas, priority-based listing, and correct handling of multiple concurrent assignments and completion rules.
Software Engineering FundamentalsOnline Assessment - CoinbaseMediumSoftware EngineerDesign an in-memory database with TTL and backups
This question evaluates skills in designing and implementing in-memory data structures, TTL-based expiration, lexicographic prefix scans, and backup/restore snapshot semantics within the Coding & Algorithms domain.
Coding & AlgorithmsOnline Assessment - CoinbaseMediumSoftware EngineerDesign cloud storage system
Design cloud storage system evaluates requirements, scale assumptions, API/data design, architecture, trade-offs, failure modes, and rollout in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
System DesignOnline Assessment - CoinbaseHardSoftware EngineerDesign scheduled payments and cancellation
A Coinbase software-engineering take-home: design a scheduled payments service that creates, lists, updates, executes, and cancels future-dated one-time and recurring transfers with exactly-once ledger correctness. It tests distributed-systems architecture, idempotent REST/gRPC API design, data modeling, concurrency control, DST handling, retries/backoff, outage backfill, and observability. The model answer pins correctness on a single-writer state machine plus an idempotent ledger.
System DesignOnline Assessment
Capital One
Circle
Citadel
Coinbase