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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 1231–1260 of 3640 results
- DoorDashMediumSoftware EngineerTrack the First Unique Restaurant in a Stream
This problem tests your ability to maintain stream uniqueness using a combination of a hash map and a doubly linked list to ensure constant-time operations.
Coding & AlgorithmsOnsiteHash MapLinked ListDesign - DoorDashMediumData ScientistWrite complex SQL on DoorDash data
This question evaluates proficiency in complex SQL querying and data manipulation, including joins across tables, time-based filtering, window functions, null and edge-case handling, aggregations, and integrating promotion and order-event data.
Data Manipulation (SQL/Python)Onsite - DropboxMediumSoftware EngineerCompute worst-case guesses for adaptive hangman
This question evaluates algorithmic problem-solving, combinatorial reasoning, and adversarial information-theoretic thinking by requiring modeling of worst-case query strategies for adaptive letter-guessing.
Coding & AlgorithmsOnsite - DropboxMediumSoftware EngineerDescribe Your Most Complex Project
This question evaluates a candidate's communication, leadership, ownership, and problem-solving competencies, specifically probing technical depth in system architecture, trade-offs, collaboration, risk management, and measurable impact.
Behavioral & LeadershipOnsite - DropboxMediumSoftware EngineerDescribe surprising project learnings
This question evaluates reflective project ownership, leadership, decision-making, communication, and the ability to derive actionable lessons from surprising findings in substantial software engineering work.
Behavioral & LeadershipOnsite - DropboxMediumSoftware EngineerDesign a recursive distributed file crawler
This prompt evaluates expertise in distributed systems, asynchronous task orchestration, recursive job scheduling, data modeling for job and file metadata, and reliability concerns such as retries, idempotency, deduplication, and partial failure handling.
System DesignOnsite - DropboxMediumSoftware EngineerDesign an S3-like Object Store
This problem evaluates your ability to design a distributed, highly available, and scalable object storage system capable of handling massive volumes of unstructured data.
System DesignOnsiteDistributed SystemsStorageScalability - DropboxMediumSoftware EngineerDesign file-processing API with long-running jobs
This question evaluates a candidate's ability to design HTTP APIs and scalable backend architectures for long-running file-processing jobs, covering competencies in API design, job orchestration, distributed systems, fault tolerance, state persistence, and idempotency.
System DesignOnsite - DropboxMediumSoftware EngineerImplement KV Store and Token Bucket
This problem tests your ability to design a thread-safe in-memory key-value store and implement a rate limiter using the token bucket algorithm.
Coding & AlgorithmsOnsiteConcurrencyData StructuresRate Limiting - DropboxMediumSoftware EngineerImplement feedback for word guessing game
This question evaluates a candidate's ability to implement string-processing, frequency-counting, and membership-validation logic to generate exact and misplaced character matches for a word-guessing game.
Coding & AlgorithmsOnsite - ExpediaMediumData ScientistAudit and onboard unfamiliar datasets safely
This question evaluates a data scientist's competency in dataset discovery, schema and key verification, profiling for distributions/missingness/timezones/currencies, duplicate and join-inflation detection, event-sequence validation, accurate metric computation, and the design of data-quality tests/data contracts within SQL/Python workflows.
Data Manipulation (SQL/Python)Onsite - ExpediaHardData ScientistChoose KPIs and prove impact with experiments
This question evaluates a data scientist's competency in KPI engineering, causal inference, experiment design, metric validation, and multi-touch attribution within the Analytics & Experimentation domain and is focused on profit-oriented search ranking.
Analytics & ExperimentationOnsite - ExpediaMediumSoftware EngineerConsolidate Three Partner APIs into a Query Service
This problem tests your ability to design a robust middleware layer that abstracts heterogeneous downstream APIs into a unified, reliable, and performant service.
System DesignOnsiteAPI AggregationMiddlewareMicroservices - ExpediaHardSoftware EngineerDesign a natural-disaster notification system
This problem tests your ability to design a high-throughput, geo-aware notification system that must deliver time-sensitive alerts to users based on their current or planned location during natural disasters.
System DesignOnsiteGeospatialScalabilityEvent-Driven - ExpediaHardSoftware EngineerDesign an employee directory with reporting queries
This question tests the ability to design a scalable hierarchical data structure, select appropriate storage backends for recursive queries, and handle write-heavy concurrent updates to organizational charts.
System DesignOnsiteDatabase ModelingHierarchical DataAPI Design - ExpediaMediumSoftware EngineerFind a Canonical Shortest Round Trip Through Flights
Find the shortest directed round trip starting and ending at a given airport, breaking ties lexicographically.
Coding & AlgorithmsOnsitegraphbfsshortest-path - ExpediaHardSoftware EngineerHow do you learn new knowledge quickly?
This question evaluates learning agility, self-directed acquisition of new technologies, and reflective leadership through concrete examples of challenging projects, testing behavioral and leadership competencies for a software engineer role.
Behavioral & LeadershipOnsite - ExpediaHardData ScientistValidate and monitor ranking model end-to-end
This question evaluates a data scientist's mastery of learning-to-rank concepts, offline evaluation and metric design, position-bias correction, diagnostic analysis, deployment safeguards, and alignment of surrogate objectives with business KPIs for hotel search ranking.
Machine LearningOnsite - FaireMediumSoftware EngineerCollaborating With and Helping an ML Engineer as an ML Infrastructure Engineer
A behavioral cross-functional collaboration question for a software engineer on a machine learning infrastructure team, posed by an ML engineer who uses the platform. It tests how you would discover an internal customer's needs, agree on priorities, communicate through changes and failures, and help them succeed.
Behavioral & LeadershipOnsite - FaireMediumMachine Learning EngineerData quality, lineage, monitoring and backfill design for an ML feature store
A discussion-based ML infrastructure design round on keeping the data behind models reliable and well governed. It covers defining and measuring availability, freshness, completeness, validity, consistency, distribution, compliance and lineage, monitoring a feature store, and planning a safe, correct data backfill.
ML System DesignOnsite - FaireMediumSoftware EngineerDesign a product likes system for a marketplace of brands and retailers
Design the backend for product likes on a marketplace where retailers like or dislike products, list the products they liked and see like counts in search results, while brands see the likes on their own products. Tests data modeling for two access directions, counter maintenance, idempotent writes and scaling the search read path.
System DesignOnsite - FaireMediumMachine Learning EngineerDesign a real-time model inference platform: deployment, scaling and monitoring
An ML system design question asking for a real-time model inference platform that teams use to serve trained models inside their applications' request paths. It tests safe model deployment and rollback, per-model autoscaling and batching, failure handling, and monitoring from infrastructure up to model quality.
ML System DesignOnsite - FaireMediumSoftware EngineerMax inherited discount and discount-source audit in a category DAG
A two-part coding problem on an e-commerce category hierarchy shaped as a DAG, where a product's applied discount is the largest discount on its category or any ancestor. The follow-up asks for an audit of which discounted categories appear in the ancestry of each bottom-level category, testing traversal order, deduplication and shared work.
Software Engineering FundamentalsOnsite - FaireMediumSoftware EngineerPeak number of bikes needed to cover all pre-booked rental intervals
Given every booking for a bike rental service as a start and end time, compute the peak number of bikes in use at the same moment, which is the smallest fleet that serves all bookings. Tests interval-overlap reasoning, half-open boundary handling and an efficient method for up to 100,000 unsorted bookings.
Coding & AlgorithmsOnsite - FaireMediumSoftware EngineerValidate assumptions and align stakeholders for a new user-permission feature
An engineer is asked how to validate the assumptions behind a new feature that changes a product's user permission model and how to reach agreement with stakeholders such as security, support and sales. Tests risk-ranked validation, safe migration of existing access, staged rollout, and turning disagreements into clear decisions.
Product / Decision MakingOnsite - FanaticsMediumSoftware EngineerClarify employment type at Microsoft
This question evaluates a candidate's ability to clearly articulate employment arrangements and the degree of ownership, accountability, performance evaluation, and measurable impact on projects, reflecting leadership, communication, and product-stewardship competencies.
Behavioral & LeadershipOnsite - FanaticsHardSoftware EngineerDesign a retail trading platform
This question evaluates a candidate's competencies in designing scalable, low-latency retail trading systems, covering system architecture, order routing and state management, market data ingestion, cash and position ledger consistency, risk controls, and compliance/observability.
System DesignOnsite - Fannie MaeMediumData ScientistDesign Test Cases for UI Change: Ensuring Quality and Functionality
Evaluates mission-aware QA collaboration for UI and backend changes in a data-science role. Strong answers compare test layers, define acceptance criteria, cover accessibility and auditability, and design robust test cases.
Behavioral & LeadershipOnsite - Fannie MaeMediumData ScientistUnderstand SQL Aggregations and Joins: Key Differences Explained
This question evaluates a candidate's competency in SQL aggregations (COUNT, SUM, AVG, MIN, MAX), join semantics (INNER, LEFT, RIGHT, FULL OUTER), set operations (UNION vs UNION ALL), window functions, view versus table trade-offs, duplicate detection and removal, query optimization techniques, and pandas DataFrame operations (merge, join, concat) within the Data Manipulation (SQL/Python) domain. It is commonly asked because it assesses both conceptual understanding (function purposes and join semantics) and practical application (writing efficient queries, deduplicating data, and translating patterns between SQL and pandas), thereby probing correctness and performance reasoning.
Data Manipulation (SQL/Python)Onsite - FigmaMediumData ScientistClarify an Ambiguous Product Question and Define a Metric
This question tests the ability to transform an abstract product objective into a rigorous measurement framework, focusing on metric selection and experimental design.
Analytics & ExperimentationOnsiteAnalyticsProduct MetricsExperimentation
DoorDash
Dropbox
Expedia
Faire
Figma