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 4351–4380 of 9403 results
- Jain GlobalMediumData EngineerBuild a Self-Service Market Data Discovery and Support Layer
This problem tests your ability to design a robust metadata-driven orchestration layer that manages data lineage, access control, and quality monitoring for financial market datasets.
Software Engineering FundamentalsTechnical ScreenSystem DesignData EngineeringMetadata - Jain GlobalEasyData ScientistDefine the p-Value, Then Explain How to Test Two Price Series for Cointegration
Two statistics questions from a systematic trading screen: give a precise definition of the p-value and its common misreadings, then explain what cointegration is and how to test two price series for it. It tests hypothesis-testing rigor, stationarity, the difference between correlation and cointegration, and multiple-testing pitfalls.
Statistics & MathTechnical Screen - Jain GlobalMediumData EngineerDesign an Incremental Rolling-Metrics Data Pipeline
Design an incremental batch data pipeline to compute multi-horizon rolling financial metrics over daily ticker observations, handling bounded historical restatements, atomic publication, and data reconciliation.
System DesignTechnical ScreenData EngineeringData PipelinesFinancial Data - Jain GlobalMediumData EngineerDesign and Debug a Point-in-Time Backtest Data Pipeline
This problem tests the ability to architect a robust financial data pipeline that ensures point-in-time accuracy and reproducible research.
System DesignTechnical ScreenData EngineeringFinancial DataBacktesting - Jain GlobalMediumData EngineerModel Effective-Dated Compliance Restrictions for Securities
This question tests the ability to design a time-series database schema capable of handling bitemporal data, identifier changes, and overlapping compliance restrictions.
System DesignTechnical ScreenData ModelingTime-SeriesBitemporal - Jane StreetHardQuantitative TraderAlternating Die-Roll Game: Optimal Accept/Reject Strategy
This question evaluates probabilistic reasoning, dynamic decision-making and zero-sum game analysis, testing competency in expected-value calculations, optimal stopping and symmetric strategic reasoning.
Software Engineering FundamentalsTechnical Screen - Jane StreetMediumQuantitative TraderAnalyze trading RFQ competitiveness data
This question tests your ability to model order flow competitiveness by deriving features from trade logs and assessing the relationship between pricing aggressiveness and win probability.
Machine LearningOnline AssessmentLogistic RegressionFeature EngineeringMarket Microstructure - Jane StreetMediumMachine Learning EngineerBoard Simulation: Bottom-Insert Pieces with Uniform Row and Column Detection
This question evaluates the ability to simulate a 2-D game board and maintain dynamic state invariants, testing array manipulation, state-tracking, and detection of uniform rows and columns under bottom-insert semantics.
Coding & AlgorithmsTechnical Screen - Jane StreetMediumSoftware EngineerBottom-Insertion Connect Game: Detect the First k-in-a-Row Winner
This question evaluates simulation and algorithmic problem-solving skills, focusing on state maintenance for an unbounded grid, efficient detection of k-in-a-row runs in rows and columns, and handling column-wise shifts that can produce simultaneous winners.
Coding & AlgorithmsTechnical Screen - Jane StreetEasyQuantitative TraderBounds on the Probability of Rain on at Least One Weekend Day
This question evaluates understanding of probability theory and dependence between events, specifically the ability to reason about bounds on the probability of a union given fixed marginals, which is a core competency for probabilistic modeling in Machine Learning and Data Scientist roles.
Machine LearningTechnical Screen - Jane StreetMediumFrontend EngineerBuild a Web Calculator That Matches a Reference App
This question evaluates frontend engineering competencies—interactive UI implementation, state management, event-driven logic, and visual layout fidelity—within the domain of software engineering fundamentals and web frontend development.
Software Engineering FundamentalsTechnical Screen - Jane StreetHardMachine Learning EngineerBuild a time-series forecasting model
Build a time-series forecasting model evaluates core ML concepts, assumptions, math intuition, training/evaluation trade-offs, and practical failure modes in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Machine LearningTechnical Screen - Jane StreetMediumSoftware EngineerCalculate win chance in three-player dice game
This question evaluates understanding of probability theory, conditional probability, and modelling of repeated stochastic events such as ties and rerolls, and is categorized under Statistics & Math.
Statistics & MathHR Screen - Jane StreetMediumMachine Learning EngineerCode Editor with Block Shrink and Expand (Code Folding)
This question evaluates a candidate's ability to model and manipulate indentation-based hierarchical structures, maintain nested visibility state for collapsed blocks, and map between original file lines and dynamic display numbering.
Coding & AlgorithmsTechnical Screen - Jane StreetMediumMachine Learning EngineerConnect-N on an Infinite Board with Gravity
This question evaluates implementation skills for efficient algorithms and data structures to manage a sparse, unbounded grid with gravity and to detect N-in-a-row runs both vertically and horizontally.
Coding & AlgorithmsTechnical Screen - Jane StreetHardSoftware EngineerDecode an Encrypted Paragraph Tree
This question evaluates skills in string parsing, tree serialization/deserialization, and bijective substitution cipher handling, assessing competency in parsing nested structures, character mapping, and traversal within the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - Jane StreetMediumSoftware EngineerDesign Exchange and Instrument Abstractions for Quote Arbitrage
Design an in-memory cross-exchange quote aggregator and arbitrage detector that identifies profitable, actionable price discrepancies while handling invalid spreads, quote staleness, and order sizing.
Software Engineering FundamentalsTechnical ScreenLow-Level DesignTrading SystemsData Structures - Jane StreetMediumQuantitative ResearcherDesign a Real-vs-Fake DNA Classifier
A Jane Street Data Scientist technical-screen question on building a classifier that distinguishes real from fake DNA sequences, given a small labeled real/fake set plus a large real-only corpus. It tests sequence representation (k-mers, embeddings, CNN/Transformer), hybrid supervised + anomaly-detection framing, realistic hard-negative generation, evaluation under class imbalance, leakage prevention, threshold calibration, and biological failure modes like reverse-complement symmetry and GC-content shortcuts.
Machine LearningTechnical Screen - Jane StreetHardMachine Learning EngineerDesign an end-to-end training framework
Design an end-to-end training framework evaluates ML product requirements, data/labeling, modeling, serving architecture, evaluation, monitoring, and trade-offs in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
ML System DesignTechnical Screen - Jane StreetHardMachine Learning EngineerDesign and implement a tiny language runtime
Design and implement a tiny language runtime evaluates requirements, scale assumptions, API/data design, architecture, trade-offs, failure modes, and rollout in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
System DesignTechnical Screen - Jane StreetEasySoftware EngineerDesign exchange–trading system message flow
This question evaluates a candidate's knowledge of distributed messaging protocols, fault-tolerant system design, and financial trading interface competencies, including defining message contracts, session management, and guarantees like idempotency and ordering.
System DesignOnsite - Jane StreetMediumQuantitative TraderDice Duel: 30-Sided Die vs. 20-Sided Die with One Blind Reroll
This question evaluates probabilistic reasoning, expected-value comparison, and decision-making under uncertainty in discrete random processes. It is commonly asked to test a candidate's ability to reason about optimal stochastic decisions and trade-offs in blind reroll scenarios, classified under probability and decision theory within the Machine Learning domain and assessing conceptual understanding rather than practical implementation.
Machine LearningOnsite - Jane StreetMediumQuantitative TraderEstimate the Number of Florists in Sydney and Make a Market
Tests Fermi estimation, sanity checking via dual perspectives (demand vs. supply/geographic), quoting a two-sided market under uncertainty, and updating beliefs given market flow or new information.
Statistics & MathTechnical ScreenFermi EstimationMarket MakingProbability - Jane StreetMediumSoftware EngineerEvaluate Expressions with Strictly Positive Integer Intermediate Results
Evaluate arithmetic expressions with a supplied decomposition helper, rejecting nonpositive or fractional intermediate results and preserving exact integer division.
Coding & AlgorithmsTechnical Screen - Jane StreetMediumFrontend EngineerField Layout: getOffset and insert
This question evaluates a candidate's ability to model and maintain ordered field layouts by computing and updating byte offsets, testing competencies in dynamic sequence data structures, cumulative offset tracking, and efficient update/query operations.
Coding & AlgorithmsTechnical Screen - Jane StreetMediumQuantitative ResearcherFive Pumpkins Weighed in Every Pair: Find the Total Weight
This question evaluates combinatorial counting, algebraic reasoning, and mental-arithmetic skills by testing understanding of pairwise sums and how individual elements contribute to aggregate totals.
Software Engineering FundamentalsOnsite - Jane StreetEasyQuantitative TraderFour Fair Coins: Expected Payoff and Pricing Two Magic Wands
The question evaluates probabilistic reasoning, expected-value computation, and invariant-based state-space analysis as applied to adaptive operations on random variables and pricing contingent instruments.
Machine LearningTechnical Screen - Jane StreetMediumSoftware EngineerImplement Connect Four with bottom push-up
This question evaluates proficiency in data structures, algorithm design, state management, and API design for game mechanics, focusing on board representation, move operations, win detection, and undo/redo functionality.
Coding & AlgorithmsOnline Assessment - Jane StreetMediumSoftware EngineerImplement a Circular Buffer
Implement a fixed-capacity circular buffer (ring buffer) supporting constant-time FIFO operations using wraparound indexing.
Coding & AlgorithmsTechnical ScreenData StructuresQueueArray - Jane StreetHardMachine Learning EngineerImplement compiler for custom language
This interview question evaluates requirements, scale assumptions, API/data design, architecture, trade-offs, failure modes, and rollout in a realistic interview setting. A strong answer for Implement compiler for custom language states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
System DesignTechnical Screen
Jane Street