Decagon interview questions

Showing 1–20 of 20 results

• Add Nested Begin, Commit, and Abort Semantics to a Shopping CartHard

  Design and implement an in-memory shopping cart that supports nested transactions via begin, commit, and abort operations with proper scope isolation.

  DecagonSoftware EngineerSoftware Engineering FundamentalsTechnical Screen
• Compute exclusive CPU time from nested logsMedium

  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.

  DecagonSoftware EngineerCoding & AlgorithmsTechnical Screen
• Count Legal Tic-Tac-Toe Games from the Empty BoardHard

  Implement an exhaustive search algorithm to count all distinct legal game sequences in 3x3 Tic-Tac-Toe, categorized by outcome.

  DecagonSoftware EngineerCoding & AlgorithmsTechnical Screen
• Deliver Messages in Fixed Batches with Per-Message Retry DelaysMedium

  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.

  DecagonSoftware EngineerSoftware Engineering FundamentalsTechnical Screen
• Design a Durable Delayed Task SchedulerHard

  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.

  DecagonSoftware EngineerSystem DesignTechnical Screen
• Design a Real-Time AI Voice SystemMedium

  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.

  DecagonSoftware EngineerML System DesignTechnical Screen
• Design a Single-Domain ChatbotMedium

  This question evaluates a candidate's ability to design production-grade conversational AI systems, testing competencies in retrieval-augmented generation, document ingestion and indexing, multi-turn session management, prompt construction, model serving, grounding and citation, safety, access control, monitoring, and operational trade-offs.

  DecagonSoftware EngineerML System DesignOnsite
• Design a Space-Efficient Versioned Recipe Shopping CartHard

  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.

  DecagonSoftware EngineerSoftware Engineering FundamentalsTechnical Screen
• Design a Tic-Tac-Toe EngineMedium

  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.

  DecagonSoftware EngineerCoding & AlgorithmsTechnical Screen
• Design an AI GatewayMedium

  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.

  DecagonSoftware EngineerSystem DesignTechnical Screen
• Design rolling-window conversation score trackerEasy

  Design a rolling-window tracker for streaming conversation scores that supports score updates, rolling average calculation, and maximum score queries.

  DecagonSoftware EngineerCoding & AlgorithmsTechnical Screen
• Design the Security Architecture for an LLM Chatbot ProductMedium

  A system design question on securing a chatbot built on a large language model that talks with people outside the company. It tests threat modeling for prompt injection and data leakage, user authentication and tool authorization outside the model, tenant isolation, sensitive-data handling, abuse controls, auditing and incident response.

  DecagonSoftware EngineerSystem DesignOnsite
• Enumerate 4x4 Tic-Tac-Toe GamesMedium

  This question evaluates understanding of recursion and backtracking, exhaustive game-tree enumeration, and state representation for combinatorial game analysis.

  DecagonSoftware EngineerCoding & AlgorithmsOnsite
• Implement CSAT tracking and call timingMedium

  This problem tests your ability to manage stateful data during event processing and calculate exclusive execution times from a stream of nested function logs.

  DecagonSoftware EngineerCoding & AlgorithmsOnsite
• Implement a CSAT Sliding Window TrackerEasy

  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.

  DecagonSoftware EngineerCoding & AlgorithmsTechnical Screen
• Send Requests in Batches of Five and Retry Failures After a Per-Request DelayMedium

  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.

  DecagonSoftware EngineerSoftware Engineering FundamentalsTechnical Screen
• Shopping Cart with Undo and Redo for Add and Remove OperationsMedium

  A coding exercise to build a shopping cart class whose add and remove operations can be undone and redone. It tests how history entries are represented, how capped removals and deleted lines are reversed exactly, what a new change does to the redo history, and how empty-history cases are handled.

  DecagonSoftware EngineerSoftware Engineering FundamentalsOnsite
• Solve 3x3 Tic-Tac-Toe with Backtracking: Perfect-Play Result and Best MoveMedium

  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.

  DecagonSoftware EngineerSoftware Engineering FundamentalsTechnical Screen
• Walk Through One Past ProjectMedium

  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.

  DecagonSoftware EngineerBehavioral & LeadershipTechnical Screen
• Walk Through a Project, a Project That Went Wrong, and How You Use AIMedium

  A culture-focused behavioral interview with three questions: describe a project you worked on, describe a project that went wrong, and explain how you use AI tools in your work. It tests clear ownership of decisions, honest reflection on failure, and practical judgment about verifying AI output and respecting its limits.

  DecagonSoftware EngineerBehavioral & LeadershipOnsite