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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.
- 9403
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- 546
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- 11
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Showing 841–870 of 2810 results
- DatologyaiHardSoftware EngineerCursor-Based Text Editor: Typing, Backspace, and Four-Way Cursor Movement
Implement a TextEditor class with a single cursor that supports typing a character, backspace, and rendering the text with a | at the cursor, then extend it with left/right and up/down cursor movement. Tests choice of representation, per-operation cost, and boundary handling across lines of different lengths.
Software Engineering FundamentalsTechnical Screen - DatologyaiEasySoftware EngineerText Editor with a Cursor: Typing, Backspace, and Four-Way Cursor Movement
Implement a text editor class that types characters at a cursor, deletes with backspace, and renders the text with a bar marking the cursor. Follow-ups add left/right and then up/down cursor movement, testing the choice of data structure for cheap edits, boundary handling, and line-aware navigation.
Software Engineering FundamentalsTechnical Screen - DatologyaiEasySoftware EngineerWord Count and Multiset Intersect Using Only a Mock Spark RDD API
Given a minimal mock of a Spark RDD with only flatMap, groupByKey, union and collect, implement a word count function and a duplicate-preserving intersect of two RDDs. Tests composing transformations without map or reduce, tracking which input an item came from, and reasoning about the cost of grouping.
Software Engineering FundamentalsTechnical Screen - DavidaiMediumSoftware EngineerDesign a Scalable Audio AI Processing Platform
Tests the candidate's ability to design a resilient, distributed ML platform for audio processing that supports both interactive and batch workloads, efficient GPU scheduling, and granular failure recovery.
ML System DesignTechnical Screenml-system-designdistributed-systemsgpu-scheduling - Deca TechnologiesMediumSoftware EngineerExplain why you want this company and leadership
This question evaluates motivation and role fit, ownership and execution, leadership experience, and cross-site collaboration by asking for reasons for joining and concrete examples of leading projects.
Behavioral & LeadershipTechnical Screen - DecagonHardSoftware EngineerAdd Nested Begin, Commit, and Abort Semantics to a Shopping Cart
Design and implement an in-memory shopping cart that supports nested transactions via begin, commit, and abort operations with proper scope isolation.
Software Engineering FundamentalsTechnical ScreenTransactionsData StructuresDesign Patterns - DecagonMediumSoftware EngineerCompute exclusive CPU time from nested logs
This question evaluates the ability to interpret execution logs and compute exclusive CPU time, testing skills in parsing structured logs, reasoning about nested execution intervals, and precise time accounting.
Coding & AlgorithmsTechnical Screen - DecagonHardSoftware EngineerCount Legal Tic-Tac-Toe Games from the Empty Board
Implement an exhaustive search algorithm to count all distinct legal game sequences in 3x3 Tic-Tac-Toe, categorized by outcome.
Coding & AlgorithmsTechnical ScreenBacktrackingDFSGame Theory - DecagonMediumSoftware EngineerDeliver Messages in Fixed Batches with Per-Message Retry Delays
Send a list of outbound messages to a provider that only accepts five per call, then retry failed messages only after the provider's own per-message cooldown has elapsed. Tests chunking, scheduling retries by readiness time instead of busy-waiting, and handling partial batch failures cleanly.
Software Engineering FundamentalsTechnical Screenschedulingretriesqueues - DecagonHardSoftware EngineerDesign a Durable Delayed Task Scheduler
Design a distributed, durable task scheduler capable of scheduling millions of tasks to execute at exact future timestamps with high precision, at-least-once delivery, and automatic fault recovery.
System DesignTechnical Screensystem-designdistributed-systemstask-scheduler - DecagonMediumSoftware EngineerDesign a Real-Time AI Voice System
This problem evaluates your ability to design a low-latency, real-time conversational AI system, focusing on component orchestration and performance trade-offs in speech processing pipelines.
ML System DesignTechnical ScreenSystem DesignReal-time SystemsStreaming - DecagonHardSoftware EngineerDesign a Space-Efficient Versioned Recipe Shopping Cart
Design an in-memory versioned shopping cart that aggregates recipe ingredients for bulk discounts, supports atomic mutations, and allows rolling back and checking out earlier cart snapshots efficiently.
Software Engineering FundamentalsTechnical Screendata-structuresdesignevent-sourcing - DecagonMediumSoftware EngineerDesign a Tic-Tac-Toe Engine
This problem tests your ability to design a state-tracking system for an n x n Tic-Tac-Toe board that allows for constant-time move validation and win detection.
Coding & AlgorithmsTechnical ScreenAlgorithmsData StructuresDesign - DecagonMediumSoftware EngineerDesign an AI Gateway
Design a high-throughput, multi-tenant AI Gateway that provides a unified API, intelligent routing, token-aware rate limiting, and observability across multiple upstream LLM providers.
System DesignTechnical ScreenAPI GatewayLLM InfrastructureRate Limiting - DecagonEasySoftware EngineerDesign rolling-window conversation score tracker
Design a rolling-window tracker for streaming conversation scores that supports score updates, rolling average calculation, and maximum score queries.
Coding & AlgorithmsTechnical ScreenSliding WindowDesignQueue - DecagonEasySoftware EngineerImplement a CSAT Sliding Window Tracker
This question evaluates the ability to design and implement efficient data structures and algorithms for a sliding time-window tracker, covering time-based expiration, stateful updates, rolling averages with rounding, and nearest-rank percentile computation.
Coding & AlgorithmsTechnical Screen - DecagonMediumSoftware EngineerSend Requests in Batches of Five and Retry Failures After a Per-Request Delay
A practical coding exercise: send a list of requests to an API that accepts at most five per call, then retry failed requests only after the per-request delay returned by the API. It tests batching, retry scheduling with timestamps, waiting without busy loops and clean handling of partial failures.
Software Engineering FundamentalsTechnical Screen - DecagonMediumSoftware EngineerSolve 3x3 Tic-Tac-Toe with Backtracking: Perfect-Play Result and Best Move
Write a backtracking solver for 3x3 tic-tac-toe that determines the result of a given position under perfect play by both sides and returns a best move for the player to move. It tests win detection, recursive game-tree search, undoing moves correctly, and reasoning about search cost, memoization and pruning.
Software Engineering FundamentalsTechnical Screen - DecagonMediumSoftware EngineerWalk Through One Past Project
This question assesses the candidate's ability to communicate complex technical work, demonstrate ownership over the development lifecycle, and justify architectural trade-offs made during a past project.
Behavioral & LeadershipTechnical ScreenSystem DesignLeadershipCommunication - DeshawHardSoftware EngineerCompare Fixed and Variable Train Gaps Without a Timetable
Compare two train services for a commuter who arrives without consulting a timetable. Explain the assumptions and derivation clearly, check edge cases, and show how the result changes when those assumptions no longer hold.
Statistics & MathTechnical Screen - DeshawMediumSoftware EngineerCompare Linux Containers and Virtual Machines
Tests in-depth understanding of Linux operating system virtualization mechanisms, contrasting hardware-level hypervisors with OS-level container isolation primitives across security, performance, and operational dimensions.
Software Engineering FundamentalsTechnical ScreenLinuxOperating SystemsDocker - DeshawMediumSoftware EngineerExplain What Happens When a Linux Shell Runs ls
Tests end-to-end understanding of Linux OS fundamentals, systems programming concepts, system calls, and how a POSIX shell interacts with the kernel to execute a command.
Software Engineering FundamentalsTechnical ScreenLinuxOperating SystemsSystem Calls - DeshawHardSoftware EngineerExplain and Compare SGD and Adam
Explain how stochastic gradient descent updates model parameters and how Adam modifies those updates using moving estimates of first and second gradient moments. Cover data and labels, leakage-safe features, baselines and model choice, offline evaluation, deployment constraints, monitoring, and drift.
Machine LearningTechnical Screen - DeshawMediumSoftware EngineerMaximum L1 Distance Between Equal-Length Subarrays
Tests recognizing that non-negative L1 terms allow reducing subarray search to full diagonal overlaps across two arrays, requiring O(n * m) time and 64-bit integer handling.
Coding & AlgorithmsTechnical Screenarraysmathtwo-pointers - DeshawMediumSoftware EngineerTeach a New Technical Concept to an Undergraduate
This exercise tests your ability to distill complex technical information, adapt to an audience's knowledge level, and maintain logical flow in a structured explanation.
Behavioral & LeadershipTechnical ScreenCommunicationMentorshipTechnical Explanation - DiscordHardSoftware EngineerImplement User Sessionization From Event Stream
This question evaluates proficiency in stream processing, stateful sessionization, time-based aggregation, and per-user metric computation, focusing on competencies such as tracking user activity across unbounded ordered event streams and computing top-channel aggregates.
Coding & AlgorithmsTechnical Screen - DisneyMediumSoftware EngineerAnswer general behavioral questions
This question evaluates behavioral competencies such as communication, teamwork, leadership, conflict resolution, adaptability, feedback exchange, prioritization, and cultural fit for a software engineering role within the Behavioral & Leadership category.
Behavioral & LeadershipTechnical Screen - DisneyHardSoftware EngineerDesign a personalized recommendation system
This question evaluates a candidate's competency in ML system design and recommender systems engineering, covering data ingestion, feature stores, candidate generation, ranking, online serving, experimentation, and operational considerations.
ML System DesignTechnical Screen - DisneyMediumSoftware EngineerImplement a Set Data Structure with a Resizable Array, Then Improve It with Hashing
Tests low-level data structure design by implementing a set from scratch using an array-backed hash table, focusing on collision resolution, dynamic resizing, load factor management, and amortized complexity.
Software Engineering FundamentalsTechnical ScreenData StructuresHash TableArrays - DisneyMediumSoftware EngineerThread-Safe Buffered Batch Writer for Streaming Records into a Database
Design and implement a thread-safe batch buffer that collects streaming records from multiple producer threads and flushes them to a database using batch inserts based on size, timeout, or shutdown triggers.
Software Engineering FundamentalsTechnical ScreenConcurrencyMultithreadingData Structures
Decagon
Discord
Disney