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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 4381–4410 of 9403 results
- Jane StreetEasyMachine Learning EngineerMarketplace Data Store: Order Matching and End-of-Day Reconciliation
This question evaluates understanding of stateful data structures, deterministic order-matching logic, and time-ordered reconciliation of transaction logs, focusing on correct handling of pricing, tie-breaking, and re-opened inventory.
Coding & AlgorithmsTechnical Screen - Jane StreetMediumQuantitative ResearcherMinimum Common Pairwise Correlation Among Seven Identically Distributed Random Variables
This question evaluates understanding of correlation constraints, covariance/correlation matrix structure, and spectral analysis, combining probability, statistics, and linear algebra competencies within the Machine Learning/Data Science domain.
Machine LearningOnsite - Jane StreetMediumQuantitative TraderOptimal Stopping for Die Rolls That Bust on Perfect Squares
This question evaluates probabilistic reasoning and optimal stopping competency, testing understanding of Markov decision processes, expected-value calculations, and risk trade-offs in stochastic processes.
Coding & AlgorithmsOnsite - Jane StreetHardSoftware EngineerOptimal Stopping with Square-Number Ruin
Analyze an optimal stopping game where a player rolls a fair six-sided die to accumulate points but busts if the running sum hits a positive perfect square. Tests dynamic programming, renewal theory intuition, and rigorous edge-case analysis under uncertain stopping boundaries.
Statistics & MathTechnical Screenprobabilityoptimal-stoppingdynamic-programming - Jane StreetHardSoftware EngineerOptimize a Two-Box Place-or-Take Game
Analyze and optimize a 100-turn, two-box stochastic game with capacity constraints and opaque states. Derive the optimal decision policy, examine boundary/edge cases, and evaluate how the strategy changes when core assumptions are relaxed.
Statistics & MathTechnical ScreenProbabilityDynamic ProgrammingMarkov Decision Process - Jane StreetHardSoftware EngineerOptimize trade PnL table updates
Design an incremental PnL tracking engine that efficiently aggregates realized and unrealized profit-and-loss across overlapping predicate views under high-frequency trade and price tick updates.
Coding & AlgorithmsOnsiteDesignData StructuresCaching - Jane StreetMediumSoftware EngineerPayout-Split Formula Where Every Step Is a Whole Positive Share
Write a parser and evaluator for arithmetic formulas that describe splitting a prize pool into whole-unit shares, where every intermediate computed amount must be a positive whole number or the entire formula is rejected. Tests recursive-descent parsing combined with evaluation rules where a single bad step invalidates the whole result.
Coding & AlgorithmsTechnical Screenparsingrecursionarithmetic - Jane StreetHardMachine Learning EngineerPredict future time-series values
This interview question evaluates ML product requirements, data/labeling, modeling, serving architecture, evaluation, monitoring, and trade-offs in a realistic interview setting. A strong answer for Predict future time-series values states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
ML System DesignTechnical Screen - Jane StreetMediumQuantitative TraderPricing a Mystery Money Box: Expected Value, Adverse Selection, and Competition
This question evaluates probabilistic reasoning and economic-incentives competencies, including expected-value calculation, risk-neutral decision-making, adverse selection, and surplus division in bargaining contexts.
Machine LearningTechnical Screen - Jane StreetMediumSoftware EngineerProcess One Million Quote Updates per Second
Design a low-latency market data processing engine capable of ingesting 1,000,000 quote updates per second across multiple exchanges, maintaining global best bids and asks, and triggering immediate cross-venue arbitrage alerts.
System DesignTechnical ScreenLow LatencyConcurrencyTrading Systems - Jane StreetHardSoftware EngineerReach a Target Using Each Number At Most Once
This question evaluates the ability to construct arithmetic expressions from a multiset of numbers and reason about combinatorial search, operator composition, parenthesization, and exact rational arithmetic under constraints.
Coding & AlgorithmsTechnical Screen - Jane StreetMediumQuantitative TraderSealed-Bid Auction for a Box of 200 Coin Flips (and an Informed Opponent)
This question evaluates understanding of probability and expected-value reasoning, auction and game-theoretic strategic thinking, Bayesian inference under asymmetric information, and quantitative decision-making relevant to a Machine Learning-focused data scientist role.
Machine LearningTechnical Screen - Jane StreetHardSoftware EngineerSnake Game: Minimum Moves to Reach the Apple
This question evaluates proficiency in state-space modeling, constrained grid pathfinding, and dynamic collision handling, testing skills in shortest-path reasoning and movement legality within the Coding & Algorithms domain; the level of abstraction is practical application of algorithmic techniques to simulate evolving game states rather than purely theoretical analysis. It is commonly asked in technical interviews because it requires reasoning about evolving constraints and reachable states, demonstrating an applicant's ability to model complex movement rules and perform effective search under limited grid and body-size constraints.
Coding & AlgorithmsTechnical Screen - Jane StreetEasyQuantitative TraderSolve probability and game-theory puzzles
This set of puzzles evaluates probabilistic reasoning, Bayesian inference, expected-value optimization, optimal stopping, and strategic game-theoretic reasoning under uncertainty and asymmetric information, situated in the Statistics & Math domain.
Statistics & MathTechnical Screen - Jane StreetMediumQuantitative TraderSolve queue switch and coin change puzzles
This two-part question evaluates probabilistic reasoning about expected waiting times with random queue switching and combinatorial/algorithmic counting for coin-change combinations, testing skills in probability, expectation and order statistics as well as combinatorics and dynamic programming within the Coding & Algorithms domain.
Coding & AlgorithmsOnline Assessment - Jane StreetEasySoftware EngineerSort trade executions into a canonical order
This question evaluates a candidate's ability to enforce deterministic ordering and data normalization of time-series trade execution records, testing competencies in multi-key sorting, tie-breaking logic, and performance with large inputs.
Coding & AlgorithmsOnsite - Jane StreetEasySoftware EngineerStack Machine Interpreter with Typed Int and String Values
This question evaluates understanding of stack-machine semantics, runtime type representation and preservation of distinct integer versus string values, plus handling mixed-type ADD behavior and output semantics.
Coding & AlgorithmsTechnical Screen - Jane StreetMediumSoftware EngineerTurning Interview Code into a Reusable Library or API
This question evaluates a candidate's skills in software design and engineering practices, including modularization, API and library interface design, documentation and typing, robustness and error handling, testing, packaging, versioning, and state/transport considerations.
Software Engineering FundamentalsTechnical Screen - Jane StreetMediumQuantitative TraderTwo Opaque Boxes: Place or Take for Maximum Expected Payoff
This question evaluates probabilistic reasoning, expected-value analysis, and sequential decision-making under uncertainty, testing competency in stochastic modeling, combinatorics, and optimization.
Coding & AlgorithmsOnsite - Jane StreetEasySoftware EngineerValidate order book data across multiple databases
This question evaluates a candidate's competency in designing data-validation and reconciliation systems for financial order books, including defining invariants, ensuring cross-database consistency, and handling edge cases like partial fills, cancels, out-of-order events, duplicates, and replayed messages.
System DesignOnsite - Jane StreetMediumQuantitative ResearcherWhich Dice Game Wins More Often: One Six in 4 Rolls, or Double Sixes in 24 Rolls?
This question evaluates probabilistic reasoning and statistical intuition, focusing on independence of trials, event probability versus expected value, and the ability to compare probabilities of rare events.
Software Engineering FundamentalsOnsite - Jane StreetMediumSoftware EngineerWrite an Interpreter for a Small Language with Load, Store and Arithmetic
Practice writing an interpreter for a small language with load, store and integer arithmetic instructions, using an assumed stack-based specification. It tests parsing source text into instructions, executing them with correct operand order, and reporting errors such as stack underflow, undefined variables and division by zero.
Software Engineering FundamentalsTechnical Screen - JefferiesEasyData ScientistHow to compute correlation from variances
Practice deriving correlation from variance identities for two random variables. The solution explains why Var(X+Y) and Var(X) alone are insufficient, derives covariance and correlation when Var(Y) is known, simplifies the equal-variance case, and checks edge cases where correlation is invalid or inconsistent.
Statistics & MathTechnical Screen - JefferiesMediumData ScientistHow to derive correlation from variances
Evaluates derivation of correlation from variance identities for two random variables. Strong answers explain why Var(X+Y) and Var(X) alone do not identify correlation, then derive covariance and correlation when Var(Y) is also known.
Statistics & MathTechnical Screen - Jump TradingHardSoftware EngineerAccelerate Tree-Model Inference
Design an end-to-end strategy to accelerate inference latency and throughput for an existing gradient-boosted decision tree (GBDT) model in a low-latency trading environment while preserving exact prediction fidelity. Address feature engineering constraints, low-level execution optimizations, verification of numerical equivalence, and production drift monitoring.
Machine LearningTechnical ScreenTree ModelsInference OptimizationLow-Latency Systems - Jump TradingEasySoftware EngineerDesign Stack Evaluators and Low-Latency Memory Primitives
This question tests your understanding of low-latency systems programming, focusing on thread-safe memory management, cache locality, and efficient expression parsing.
Software Engineering FundamentalsTechnical ScreenC++ConcurrencyLow-Latency - Jump TradingHardSoftware EngineerDesign a Compact Columnar File Format
Design an append-friendly, compact columnar file format optimized for fast analytical scans over tabular financial market data (e.g., tick feeds or order book snapshots). Define the on-disk binary layout, reader/writer abstractions, serialization rules, and operational trade-offs.
Software Engineering FundamentalsTechnical Screensystems-designfile-formatscolumnar-storage - Jump TradingEasySoftware EngineerExpand a Serial and Parallel Task Composition Specification
Tests parsing structured workflow specifications with nested delimiters and quoted literals, then generating all concrete serial execution paths via Cartesian expansion.
Coding & AlgorithmsOnline AssessmentString ParsingRecursionBacktracking - Jump TradingMediumSoftware EngineerExplain C++ vector, unordered_map, and virtual functions
Explain C++ vector, unordered_map, and virtual functions 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 - Jump TradingEasySoftware EngineerFind the Largest Equivalence Class of Fractions
This problem tests your ability to handle numerical equivalence using canonical representations to avoid floating-point precision issues.
Statistics & MathTechnical ScreenMathHash MapNumber Theory
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