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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 1081–1110 of 4616 results
- Capital OneHardData ScientistPrevent data registration outage and reduce loss
This question evaluates competency in production data reliability, monitoring and alerting, incident response, reconciliation, and cross-functional leadership for analytics pipelines.
Behavioral & LeadershipTechnical Screen - Capital OneMediumData ScientistQuantify database bug cost/benefit
This question evaluates a candidate's ability to perform cohort-based financial impact analysis and basic statistical arithmetic to quantify revenue and cost deltas caused by registration-state errors.
Statistics & MathTechnical Screen - Capital OneMediumData ScientistReconcile ledgers with SQL/Python and late events
This question evaluates a candidate's ability to implement data reconciliation and ETL engineering skills, including SQL window functions and joins, time-based FX rate lookups, matching logic for late-arriving events, idempotent daily pipeline design with deterministic keys and exactly-once semantics, and basic statistical charting in Python.
Data Manipulation (SQL/Python)Technical Screen - Capital OneMediumSoftware EngineerRemove nodes with a given value
This problem tests your ability to manipulate singly linked lists, specifically handling edge cases like removing head nodes and reassigning pointers in a single pass.
Coding & AlgorithmsTechnical ScreenLinked ListPointersRecursion - Capital OneMediumData ScientistSegment 500k users into three groups
This question evaluates a candidate's competency in data-driven customer segmentation, expected-revenue modeling, and trade-off analysis between churn risk and monetization.
Analytics & ExperimentationTechnical Screen - Capital OneMediumData AnalystSet a Minimum Sale Price After Audience Loss and Reinvestment
Calculate a show’s minimum sale price using lost audience value and reinvestment profit, then assess a 60-million-dollar offer.
Analytics & ExperimentationTechnical Screen - Capital OneEasyData AnalystShould a Restaurant Partner with Groupon?
This question evaluates a candidate's competence in unit economics, break-even and profitability modeling, and the ability to distinguish incremental versus cannibalized customers when assessing voucher-based promotional partnerships, reflecting skills in revenue modeling, cost accounting, and business analytics.
Analytics & ExperimentationTechnical Screen - Capital OneMediumData ScientistSketch function from derivatives and limits
This question evaluates understanding of calculus concepts—derivatives, concavity, limits, and continuity—and the ability to interpret derivative sign patterns to infer monotonicity and locate extrema.
Statistics & MathTechnical Screen - Capital OneMediumSoftware EngineerSort Matrix Diagonals By Their Values
Tests matrix traversal along anti-diagonals, string formation, and custom multi-key sorting with deterministic tie-breaking.
Coding & AlgorithmsTechnical Screenmatrixsortingstrings - Capital OneMediumData ScientistTest and Run a Reproducible Data Science Pipeline
Design and implement a robust, testable Python data pipeline class that validates input data schemas, handles feature transformation, logs execution metrics, and produces versioned outputs. Write targeted unit and integration tests ensuring graceful failure on corrupted inputs.
Software Engineering FundamentalsTechnical ScreenPythonData PipelinesTesting - Capital OneHardData ScientistUse data to resolve an ambiguous problem
This question evaluates a data scientist's competency in end-to-end data analysis, causal identification, statistical modeling, data quality and governance, bias assessment, and communication of uncertainty when addressing an ambiguous business problem.
Behavioral & LeadershipTechnical Screen - Capital OneMediumSoftware EngineerVirtual Card Numbers Case: Trade-offs, Payment Validation Rules, Debugging
A three-stage case interview on virtual credit card numbers. It covers the benefits and problems of virtual cards for cardholders and the issuer, a hand walkthrough that validates payments against digit-by-digit card number rules, and debugging messy validator code for inverted boolean operators and boundary errors.
Software Engineering FundamentalsTechnical Screen - Capital OneMediumData ScientistWhy Retain Phone Channel Despite Lower Profitability?
This interview question evaluates behavioral evidence, ownership, communication, trade-offs, and measurable outcomes in a realistic interview setting. A strong answer for Why Retain Phone Channel Despite Lower Profitability? states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Behavioral & LeadershipTechnical Screen - Capital OneMediumData ScientistWrite SQL for lowest price with ratings
This question evaluates SQL data-manipulation skills including aggregation, conditional filtering, NULL handling, grouping, and deterministic ordering, and sits in the Data Manipulation (SQL/Python) domain with an emphasis on practical application of query writing rather than purely conceptual design.
Data Manipulation (SQL/Python)Technical Screen - Capital OneMediumData ScientistWrite SQL to find top net-revenue products
This question evaluates proficiency in SQL data manipulation, including joins, aggregations, date-window filtering, handling returns and net-revenue calculations, plus the use of analytic/window functions for per-category ranking and tie-breaking.
Data Manipulation (SQL/Python)Technical Screen - CargurusMediumData ScientistAssess a Distribution and Derive Coin-Toss Expectations
This problem tests the ability to distinguish between Bernoulli and Binomial processes, calculate expected values and variances, and validate model assumptions based on observed sample data.
Statistics & MathTechnical ScreenProbabilityStatisticsMLE - CargurusMediumData ScientistReverse a Character Array In Place
This problem tests the ability to manipulate array elements in-place using two-pointer logic while adhering to strict space complexity constraints.
Coding & AlgorithmsTechnical ScreenArraysTwo PointersIn-place - CensysMediumFrontend EngineerAdd Case-Insensitive Search to a Support Ticket Queue UI and Debug Its Behavior
A frontend exercise on an existing support ticket queue with Unresolved and Archived tabs, a ticket list and an activity panel: make the search box filter tickets by title or assignee regardless of letter case, then debug parts of the app that misbehave. It tests reading unfamiliar code, state design and systematic debugging.
Software Engineering FundamentalsTechnical Screen - CerebrasHardSoftware EngineerDesign a Multi-Channel Message Queue
This question evaluates understanding of data modeling for multi-tag messages, set-based subscription semantics, scalable system design, and algorithmic complexity for operations such as enqueue, dequeue, subscribe/unsubscribe, and intersection queries.
System DesignTechnical Screen - CerebrasMediumSoftware EngineerExplain Learning and Conflict Approaches
This question evaluates a candidate's ability to learn in ambiguous technical domains, manage disagreements with senior colleagues, and adopt efficient learning approaches—assessing adaptability, communication, prioritization, and leadership competencies.
Behavioral & LeadershipTechnical Screen - CerebrasMediumSoftware EngineerImplement Binary Search in C++
This question evaluates proficiency in implementing binary search in C++, focusing on iterative control flow, correct handling of not-found cases, boundary conditions, and understanding of algorithmic correctness.
Coding & AlgorithmsTechnical Screen - CerebrasMediumSoftware EngineerImplement and Optimize Vector Multiplication
This question evaluates a candidate's ability to implement vector–vector multiplication and to reason about performance optimizations and sparse data structures, assessing competencies in algorithm design, parallel computing, memory hierarchy, and numerical operations.
Coding & AlgorithmsTechnical Screen - ChalkMediumSoftware EngineerCompute rainwater accumulation on a height grid
Tests the ability to simulate 2D fluid accumulation using priority-queue-based graph traversal (similar to Dijkstra's algorithm) to track spilling boundaries.
Coding & AlgorithmsTechnical Screenheapbfsgraph - Character.AIMediumSoftware EngineerFind Shortest Covering Substring
This problem tests your ability to use the sliding window technique and hash maps to find the smallest window in a string that contains all characters of a target pattern.
Coding & AlgorithmsTechnical ScreenSliding WindowHash MapTwo Pointers - Character.AIMediumData ScientistWrite SQL for character safety and engagement metrics
This question evaluates proficiency in SQL-based data manipulation and analytics, specifically aggregations, joins, date-based grouping, ratio calculations, and windowed moving averages to compute safety and engagement metrics.
Data Manipulation (SQL/Python)Technical Screen - ChariotMediumSoftware EngineerExplore an HTTP Maze
This question evaluates the ability to integrate HTTP-based APIs with graph traversal and state management, covering concepts such as breadth-first exploration for shallow-first search, cycle avoidance, transient error handling, and key-lock resource constraints.
Coding & AlgorithmsTechnical Screen - Charta HealthMediumSoftware EngineerMake Token-Bucket Admission Safe Across Threads
Tests your ability to implement a thread-safe token bucket rate limiter with lazy refill, monotonic time tracking, and blocking admission control.
Software Engineering FundamentalsTechnical Screenconcurrencymultithreadingrate-limiting - Chicago Trading CompanyMediumSoftware EngineerBuild an Ordered Latest-Quote Container
Build an insertion-ordered container that stores only the latest quote for each stock symbol. Support expected O(1) push, pop, and size operations while updating bid and ask values without changing a symbol's original position and safely rejecting malformed commands.
Coding & AlgorithmsTechnical Screen - Chicago Trading CompanyMediumSoftware EngineerDescribe Growth, Mistakes, and Obstacles
This question assesses the candidate's ability to reflect on professional setbacks, demonstrate accountability, and translate constructive criticism into measurable skill growth.
Behavioral & LeadershipTechnical ScreenBehavioralAccountabilityMentorship - Chicago Trading CompanyMediumSoftware EngineerImplement a Constant-Time Simple Moving Average
Implement a fixed-window simple moving average with O(1) processing for every valid add and query. Maintain a rolling sum and bounded queue, average the samples available before the window fills, and return deterministic results for empty, malformed, or unknown operations.
Coding & AlgorithmsTechnical Screen
Capital One
Cerebras