practice a little every day, paws crossed ♡
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 2911–2940 of 9403 results
- DoorDashMediumSoftware EngineerBuild a Three-Service Refund Workflow over HTTP
Implement and orchestrate a multi-service refund pipeline over HTTP, ensuring idempotent execution, safe concurrency limits, and crash recovery across separate process boundaries.
Software Engineering FundamentalsTechnical Screendistributed-systemshttp-apisidempotency - DoorDashHardData ScientistBuild a late-delivery risk model
This question evaluates competencies in production-ready predictive modeling, including target definition, feature engineering, temporal train/validation splitting to avoid leakage, model evaluation and calibration, monitoring and ramp strategies, and translating probabilistic outputs into business-impacting decisions for a Data Scientist.
Machine LearningOnsite - DoorDashMediumSoftware EngineerBuild an Order-Exception Microservice with Explicit Refund Policies
Design and demonstrate a local service for missing or delayed orders, with explicit refund rules, duplicate handling, and auditable decisions.
Software Engineering FundamentalsOnsite - DoorDashMediumSoftware EngineerBuild and Debug a Dasher-to-Order Assignment Service, Then Prepare It for Production
A DoorDash onsite exercise to finish and debug starter code for a service that assigns delivery drivers to orders. It tests constant-time bookkeeping, defending a list versus hash map storage choice, invariant-based testing, and how to make the service safe and scalable in production.
Software Engineering FundamentalsOnsite - DoorDashMediumSoftware EngineerCalculate Courier Earnings
This question evaluates algorithmic problem-solving with emphasis on temporal interval aggregation, handling overlapping events, and applying conditional rate multipliers under specified business rules.
Coding & AlgorithmsTechnical Screen - DoorDashHardSoftware EngineerCalculate Daily Driver Pay
This question evaluates event-driven time-interval processing, interval-overlap arithmetic, rate computation, and robustness to malformed, duplicate, or unordered events when aggregating a driver's pay from a day's log.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerCalculate Driver Payments
Implement a payout calculation system for delivery drivers by deduplicating order logs, merging overlapping active-time intervals, and computing base pay, delivery bonuses, and tips.
Coding & AlgorithmsOnsiteintervalssortinghash-table - DoorDashMediumData ScientistCalculate Late Delivery Percentage and Top Customers
This question evaluates data manipulation and aggregation skills for a Data Scientist role, focusing on date handling, computing the percentage of late orders, and ranking customers using SQL or Python.
Data Manipulation (SQL/Python)Technical Screen - DoorDashEasyData ScientistCalculate Monthly Restaurant Sales Growth
This problem tests the ability to aggregate transactional data by month and use window functions to calculate percentage growth between consecutive periods while handling null values.
Data Manipulation (SQL/Python)Technical ScreenSQLWindow FunctionsAggregation - DoorDashHardData ScientistCalculate Order Request Metrics
This question evaluates SQL and data-manipulation competencies for computing order-level metrics, including aggregations, joins, windowed event sequencing, timestamp/timezone handling, and NULL-aware comparisons.
Data Manipulation (SQL/Python)Onsite - DoorDashMediumData ScientistCalculate power and test duration
This question evaluates proficiency in statistical power analysis, sample size calculation for proportions, hypothesis testing for two-sided z-tests, and practical experiment duration estimation for A/B testing.
Statistics & MathTechnical Screen - DoorDashHardSoftware EngineerCompare front-end state management approaches
DoorDash software-engineer onsite front-end question: compare Redux with modern state and data management approaches (Redux Toolkit/RTK Query, React Query, SWR, Zustand, Recoil, MobX, Context) and design an end-to-end strategy for a React SPA that needs offline viewing, pagination, optimistic updates, and error retries. It tests separating client UI state from server cache, caching/invalidation, performance, type safety, testing, and an incremental migration plan off Redux.
Software Engineering FundamentalsOnsite - DoorDashEasySoftware EngineerCompute Courier Delivery Pay
This question tests the ability to handle time intervals and calculate cumulative earnings based on overlapping delivery pay rates.
Coding & AlgorithmsTechnical ScreenArraysIntervalsGreedy - DoorDashMediumSoftware EngineerCompute Differences Between Catalog Trees
This question evaluates proficiency in tree algorithms and hierarchical data comparison, including simultaneous traversal, subtree sizing, key-based node identity, and time/space complexity reasoning, and is commonly asked to assess algorithmic problem-solving and trade-off analysis when comparing structured datasets.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerCompute Driver Pay with Double-Pay Windows
This question evaluates a candidate's ability to perform interval arithmetic and aggregation for time-based pay computations, including handling overlapping intervals, half-open boundaries, capped double-pay application, and special-case handling for canceled orders.
Coding & AlgorithmsTechnical Screen - DoorDashEasySoftware EngineerCompute Nearest Destination Distances
This problem tests your ability to use Multi-Source Breadth-First Search (BFS) to find the distance from every empty cell to the nearest destination in a grid.
Coding & AlgorithmsTechnical ScreenBFSGraphsGrid - DoorDashMediumSoftware EngineerCompute cart total with best promotion
This question evaluates numerical reasoning for monetary calculations, handling of multiple promotion types, precision and rounding considerations, and edge-case handling such as empty carts and clamping totals within the Coding & Algorithms domain.
Coding & AlgorithmsOnsite - DoorDashMediumSoftware EngineerCompute courier pay with peak-hour rules
This question evaluates a candidate's data manipulation skills and competency in implementing business rules, including robust error handling, aggregation for per-day totals, minimum-pay enforcement, and time-window (peak-hour) pay adjustments.
Data Manipulation (SQL/Python)Technical Screen - DoorDashMediumSoftware EngineerCompute dasher pay from deliveries
This question evaluates competency in data manipulation, schema design and validation, time-based aggregation, pay-computation logic, and handling of edge cases using SQL or Python.
Data Manipulation (SQL/Python)Onsite - DoorDashMediumSoftware EngineerCompute dasher pay with peak-hour query
This question tests the ability to handle overlapping time intervals and perform weighted calculations based on time-based pay multipliers.
Coding & AlgorithmsOnsiteAlgorithmsIntervalsData Processing - DoorDashMediumSoftware EngineerCompute dasher payout from API data
This question evaluates a candidate's proficiency in data manipulation and transaction aggregation using SQL or Python, encompassing time-zone-aware timestamp handling, pagination, late or missing events, cancellations and negative adjustments, rounding rules, and itemized breakdowns.
Data Manipulation (SQL/Python)Onsite - DoorDashMediumSoftware EngineerCompute delivery times on a grid
This question evaluates understanding of graph traversal and shortest-path algorithms, grid-based pathfinding, and data structure selection for representing sparse or large grids within the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerCompute earliest arrival in time-grid
This question evaluates algorithmic problem-solving and pathfinding skills on grid-based graphs, focusing on modeling time-dependent traversal constraints and reasoning about efficient search and supporting data structures.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerCompute nearest dashmart and busiest assignments
Compute nearest dashmart and busiest assignments 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 EngineerCompute nearest dashmart distances for queries
This question evaluates a candidate's understanding of graph traversal and shortest-path computation on grids, spatial reasoning about obstacles and sources, and the ability to analyze algorithmic scalability and complexity when answering many queries.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerCompute nearest-exit distances in a grid
Compute nearest-exit distances in a grid 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 - DoorDashMediumData ScientistCompute rolling cold-delivery rates with windows
This question evaluates proficiency with SQL window functions, time-based joins, event deduplication and business-rule implementation for computing rolling metrics over temporal windows.
Data Manipulation (SQL/Python)Onsite - DoorDashMediumData ScientistCompute sample sizes and error control
This question evaluates proficiency in experimental design and applied inferential statistics—specifically sample size calculation for means and proportions, non-inferiority testing, multiple-comparison error control, cluster-randomized design effects, and sequential monitoring boundaries—within the Statistics & Math domain for a Data Scientist role. It is commonly asked to measure the ability to apply statistical formulas and error-control principles under practical constraints, balancing power and type I error while accounting for clustering and interim looks; the assessment emphasizes practical application grounded in conceptual understanding of inferential methods.
Statistics & MathTechnical Screen - DoorDashHardSoftware EngineerCount changed nodes between two menu trees
This problem tests recursive tree traversal and hierarchical diffing strategies to identify structural and content changes between two versions of a menu tree.
Coding & AlgorithmsTechnical ScreenTreesRecursionHash Maps - DoorDashMediumSoftware EngineerCount changed nodes in N-ary trees
This question evaluates understanding of N-ary tree data structures, structural comparison of hierarchical versions, and the ability to reason about time and space complexity when detecting added, deleted, value-changed, or reparented nodes.
Coding & AlgorithmsTechnical Screen
DoorDash