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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.
- 9403
- Questions
- 546
- Companies
- 11
- Topics
- 8
- Languages
Showing 3061–3090 of 9403 results
- DoorDashHardSoftware EngineerFind longest common ordered restaurant list
This question evaluates a candidate's understanding of sequence algorithms, dynamic programming, and string/list manipulation by requiring computation of the longest common subsequence between two ordered lists of restaurant IDs.
Coding & AlgorithmsOnsite - DoorDashMediumSoftware EngineerFind names similar by one swap
This question evaluates string manipulation, character-frequency analysis, and algorithmic reasoning to determine near-matches under a single-character-swap constraint.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerFind the Minimum Delivery Processing Speed
This problem tests binary search on the answer space to find the minimum throughput capacity required to process a set of delivery orders within a fixed deadline.
Coding & AlgorithmsOnsiteBinary SearchOptimizationMath - DoorDashMediumSoftware EngineerFind the Minimum Parenthesis Deletions and Their Positions
This problem tests string manipulation, stack-based parsing, and greedy logic to identify the indices of parentheses that must be removed to transform a string into a valid sequence.
Coding & AlgorithmsOnsiteStringsStackGreedy - DoorDashMediumSoftware EngineerFix a Round-Robin Load Balancer, Then Implement Consistent Hashing
A debugging-style coding round on request routing: make a round-robin load balancer behave correctly as servers join and leave, then implement consistent hashing so requests with the same key stay on the same server. It tests careful state handling, concurrency, edge cases such as an empty pool, and reasoning about how many keys move when membership changes.
Software Engineering FundamentalsOnsite - DoorDashMediumData ScientistGenerate Weekly Revenue and Engagement Summary with Pandas
This question evaluates proficiency in data manipulation and analytics with Pandas and SQL, covering aggregations, distinct purchase counts, lambda-based user-tier classification, and platform-level conversion-rate computation.
Data Manipulation (SQL/Python)Technical Screen - DoorDashMediumSoftware EngineerGenerate the next lexicographic array arrangement
This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Generate the next lexicographic array arrangement states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsOnsite - DoorDashHardSoftware EngineerHandle a payment-service incident with resource spikes
Handle a payment-service incident with resource spikes 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 & LeadershipTechnical Screen - DoorDashEasySoftware EngineerHandle payment-service outages
This question evaluates a candidate's competence in designing fault-tolerant payment workflows and operational resilience, covering concepts such as idempotency, retry strategies, queuing and dead-letter handling, circuit breaking, reconciliation, and monitoring.
Software Engineering FundamentalsOnsite - DoorDashMediumSoftware EngineerHandling Duplicate Upstream Order Records in Dasher Pay Calculation
Explain how a Dasher pay calculation driven by upstream order records stays correct when those records contain duplicates. Tests deciding when two records describe the same fact, making processing safe against replayed records, handling conflicting and late data or corrections after payout, and preventing double payouts.
System DesignTechnical Screen - DoorDashEasySoftware EngineerHow do you discuss mistakes and trade-offs?
This question evaluates competency in accountability, leadership, incident management, and product/operational decision-making within the Behavioral & Leadership domain for software engineers.
Behavioral & LeadershipOnsite - DoorDashHardSoftware EngineerHow to prepare for AI-assisted coding interviews?
Tests your ability to critically evaluate, debug, and refactor AI-generated code for a real-time order batching service under concurrent access, edge-case constraints, and strict correctness requirements.
Software Engineering FundamentalsOnsiteconcurrencysystem-designrefactoring - DoorDashMediumData ScientistHow would you mentor junior teammates?
A DoorDash Data Scientist onsite behavioral & leadership question that asks how you mentor others as a senior IC — especially more junior teammates. Strong answers diagnose each person's gaps, tailor support across levels and cross-functional partners, use concrete mechanisms (ramp plans, feedback rubrics, scalable templates, sponsorship), mentor through influence rather than authority, and measure effectiveness via independence and impact, all anchored in a detailed STAR example.
Behavioral & LeadershipOnsite - DoorDashMediumMachine Learning EngineerHow would you prevent wrong items in deliveries?
This question evaluates systems thinking, root-cause analysis, metrics-driven decision-making, and cross-functional leadership in operational product-process contexts.
Behavioral & LeadershipOnsite - DoorDashEasyData ScientistHow would you test a bike delivery option?
This problem tests the ability to design an A/B test, define success metrics, and account for confounding variables when introducing a new logistics channel (bike delivery) to a marketplace.
Analytics & ExperimentationTechnical ScreenA/B TestingMetricsMarketplace Analytics - DoorDashMediumData ScientistIdentify Challenges and Solutions for Bike-Delivery Program
Evaluates operational and strategic thinking for a bike-delivery courier program. Strong answers identify marketplace, safety, weather, regulatory, courier, merchant, customer-experience, and unit-economics risks, then pair each challenge with practical mitigations and measurable rollout guardrails.
Behavioral & LeadershipTechnical Screen - DoorDashHardData ScientistIdentify Key Drivers of Delivery Decline in Los Angeles
This interview question evaluates metric design, causal reasoning, experiment setup, diagnostics, SQL/statistical checks, and recommendations in a realistic interview setting. A strong answer for Identify Key Drivers of Delivery Decline in Los Angeles states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Analytics & ExperimentationTechnical Screen - DoorDashMediumSoftware EngineerIdentify members lacking specialty coverage
Identify members lacking specialty coverage 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 & AlgorithmsOnsite - DoorDashHardSoftware EngineerImplement Bootstrap-like responsive utility classes
This question evaluates proficiency in front-end engineering, including CSS utility system design, responsive grid layout, semantic HTML, accessibility (ARIA and focus management), form validation, asynchronous submission patterns, and lightweight JavaScript for interactivity and telemetry.
Software Engineering FundamentalsOnsite - DoorDashMediumSoftware EngineerImplement Timeout Refund Workflow
Design and implement a stateful, idempotent refund workflow manager that safely handles gateway timeouts, retries, and duplicate requests.
Coding & AlgorithmsOnsiteState MachineIdempotencySystem Design - DoorDashMediumSoftware EngineerImplement a Consistent Hash Ring
This problem tests your ability to implement a distributed hashing mechanism that minimizes data movement when adding or removing nodes.
Software Engineering FundamentalsOnsiteHashingDistributed SystemsData Structures - DoorDashMediumSoftware EngineerImplement a Resilient Aggregator over Three Services
Implement an asynchronous aggregation service that orchestrates calls to User, Payment, and Address downstream clients with dependency-aware concurrency, partial failure handling, and deadline enforcement.
Software Engineering FundamentalsOnsiteConcurrencyAsyncIOAPI Design - DoorDashEasySoftware EngineerImplement a consistent hashing ring
This question evaluates understanding of consistent hashing, virtual nodes, deterministic hash functions, and data structure design for efficient key-to-server mapping and dynamic membership changes.
Coding & AlgorithmsOnsite - DoorDashMediumSoftware EngineerImplement a hierarchical key-value store
Implement a hierarchical key-value store 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 & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerImplement a simple service with tests
Implement a simple service with tests 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 & AlgorithmsOnsite - DoorDashMediumSoftware EngineerImplement and compare round-robin and consistent hashing
This question evaluates a candidate's ability to implement and reason about load balancing algorithms (round-robin and consistent hashing), covering competencies in data structures, hashing, concurrency, correctness, and unit testing.
Coding & AlgorithmsOnsite - DoorDashMediumSoftware EngineerImplement consistent hashing ring
This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Implement consistent hashing ring states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerImplement dasher active-time calculator
This question evaluates competency in time-based event processing, pairing related events, computing durations using LocalDateTime and Duration APIs, and analyzing algorithmic time and space complexity.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerImplement image carousel with comments and upvotes
This question evaluates a candidate's ability to design scalable data structures and efficient algorithms for interactive features, including API design, pagination, and consistency/concurrency handling for upvotes and per-image comment threads.
Coding & AlgorithmsOnsite - DoorDashMediumSoftware EngineerImplement round-robin load balancer
This question evaluates a candidate's ability to implement a strict round-robin load balancer with O(1) average operations while handling concurrent nextServer and update calls, health-check-driven skipping, and failure scenarios, testing competencies in data structures, concurrent programming, and fault-tolerant system behavior.
Coding & AlgorithmsOnsite
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