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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.
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Showing 331–360 of 781 results
- HeadlandsMediumData ScientistWhat Cross-Validation Reduces: Bias, Variance, Type I or Type II Error
This question tests your conceptual understanding of how k-fold cross-validation affects the generalization error and how the choice of 'k' influences the trade-off between bias and variance in model performance estimation.
Machine LearningOnline AssessmentModel EvaluationCross-ValidationStatistics - HeadlandsMediumData Scientistt-Stat With an Added Orthogonal Regressor, Live Sharpe Check, and Absolute-Loss Estimator
Solve three core quantitative problems covering OLS regression mechanics under orthogonal regressors, statistical significance of backtested Sharpe ratios in live deployment, and loss-function minimization for L1 error.
Statistics & MathOnline AssessmentEconometricsSharpe RatioLinear Regression - HouzzMediumSoftware EngineerConvert a Column Number to an Excel-Style Label
Convert one-based spreadsheet columns into A-through-Z and AA-through-ZZ labels, with correct handling of multiples of 26.
Coding & AlgorithmsOnline Assessment - HubSpotMediumSoftware EngineerDesign a bank with scheduled payments and merges
This question evaluates data-structure and algorithm design competencies with emphasis on concurrency, time-based scheduling, aggregation (TopK), transactional consistency, idempotency, and merge semantics for an in-memory banking service, falling under the Coding & Algorithms and system-design domain.
Coding & AlgorithmsOnline Assessment - HubSpotMediumSoftware EngineerDesign and implement a bank account system
This question evaluates a candidate's skills in system design, data modeling, transactional integrity, concurrency control, idempotency, API design, and algorithmic complexity for implementing a minimal banking service.
Coding & AlgorithmsOnline Assessment - HubSpotMediumSoftware EngineerImplement account CRUD and transfer
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 account CRUD and transfer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsOnline Assessment - HubSpotMediumSoftware EngineerSchedule and execute future payments
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 Schedule and execute future payments states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
System DesignOnline Assessment - Hudson River TradingMediumData ScientistCount Smaller Numbers with Only Zero and One in Base Four
Count the number of positive integers strictly less than n whose base-4 representation consists only of the digits 0 and 1.
Coding & AlgorithmsOnline AssessmentMathBit ManipulationDigit DP - Hudson River TradingMediumQuantitative ResearcherImplement Buffer Parsers and Generic Map Class
This problem tests your ability to safely parse binary data streams from raw memory buffers and implement a type-safe generic wrapper around standard associative containers.
Coding & AlgorithmsOnline AssessmentC++TemplatesBinary-Parsing - IBMMediumSoftware EngineerBreak Adjacent Duplicate Characters
Tests string traversal, run-length counting, and greedy optimization to determine the minimum character replacements needed to eliminate adjacent identical characters across a list of words.
Coding & AlgorithmsOnline AssessmentStringsGreedyAlgorithms - IBMEasySoftware EngineerCalculate Revenue from Highest-Inventory VM Sales
Sell each VM unit at its current inventory count, always choose a type with maximum inventory, and compute total revenue safely.
Coding & AlgorithmsOnline Assessment - IBMMediumSoftware EngineerCount Replacements Needed to Separate Equal Adjacent Characters
This problem tests your ability to identify and process consecutive character runs in strings and apply greedy calculations to minimize replacement operations.
Coding & AlgorithmsOnline AssessmentGreedyStringsArray - IBMMediumSoftware EngineerCount Tree Vertices with Pythagorean Distances
Calculate distances from three fixed vertices to all other vertices in an unweighted tree and count those whose strictly positive distances form a Pythagorean triple.
Coding & AlgorithmsOnline AssessmentTreesBFSGraph - IBMMediumSoftware EngineerDebug and Harden a Ticketing Backend API
Implement and harden an in-memory ticket service backend to handle deterministic cursor pagination, idempotent reservations, cache invalidation, and oversell prevention.
Software Engineering FundamentalsOnline AssessmentAPI DesignCachingPagination - IBMMediumSoftware EngineerDescribe open-source contribution experience
This IBM software-engineer take-home behavioral question evaluates your open-source contribution experience end to end: the projects and repositories you worked on, your specific roles and most impactful contributions, how you collaborated with maintainers through issues, code reviews, and RFCs, and the lessons you took from code reviews and issue triage. A strong answer goes deep on one or two repositories with quantified, evidence-backed impact.
Behavioral & LeadershipOnline Assessment - IBMHardSoftware EngineerDesign a multithreaded CPU 1D convolution
An IBM software-engineer take-home that asks you to design and implement a multithreaded CPU version of valid 1D convolution across three regimes: a tiny kernel (K=3), a kernel as long as the input (K=N, a single dot product), and a 100-thread cap. It evaluates parallel decomposition, scheduling, cache locality, false-sharing avoidance, SIMD vectorization, and reduction/synchronization choices.
System DesignOnline Assessment - IBMMediumSoftware EngineerFind Customers Whose Average Website Resource Usage Exceeds 50 Percent
Practice PostgreSQL aggregation with HAVING, customer-level average resource utilization, strict thresholds, two-decimal rounding, and ascending email output.
Data Manipulation (SQL/Python)Online Assessment - IBMMediumSoftware EngineerManage Authentication Tokens with a Fixed Time to Live
Design an authentication token manager that handles token generation, renewal, and active token counting based on a fixed time-to-live.
Coding & AlgorithmsOnline AssessmentHash MapDesignQueue - IBMMediumSoftware EngineerMaximize Revenue from Depleting VM Inventory
This problem tests your ability to efficiently manage and update a dynamic collection of items using a priority queue to always extract the maximum value.
Coding & AlgorithmsOnline AssessmentBinary SearchGreedyOptimization - IBMMediumSoftware EngineerMaximize Revenue from Depleting VM Stock
Tests greedy optimization, sorting, and arithmetic progression math to compute maximum revenue from diminishing-value stock with large order quantities.
Coding & AlgorithmsOnline Assessmentgreedybinary-searchmath - IBMMediumSoftware EngineerSix Timed Behavioral Prompts: AI Tools, Debugging, Teamwork, Explaining, Goals, Quality
Six prompts from a recorded behavioral interview, each with one minute to prepare and three minutes to answer: vetting an AI tool's output, diagnosing a failure, teamwork, explaining your work, reaching a goal, and verifying that something you built works. Tests structured, specific storytelling under strict time limits.
Behavioral & LeadershipOnline Assessment - IBMEasySoftware EngineerSum Pairwise Remainders Across Two Integer Ranges
Calculate the total sum of remainders obtained by taking each integer in a dividend range modulo each non-zero divisor in a divisor range. The problem tests division properties, edge-case handling for zero divisors, and avoiding integer overflow.
Coding & AlgorithmsOnline AssessmentMathAlgorithmsArithmetic - IBMEasySoftware EngineerSum the XOR of Every Cross-Array Pair
Tests bitwise frequency analysis and arithmetic optimization by reducing an O(N * M) cross-product XOR sum to an O(B * (N + M)) bit-by-bit contribution calculation.
Coding & AlgorithmsOnline Assessmentbit-manipulationmatharrays - IBMEasyData ScientistWrite SQL to compute max and min marks
This question evaluates a candidate's ability to perform basic data aggregation in SQL, specifically computing summary statistics from a single table. It is commonly asked to assess competence in data manipulation and query result shaping within the Data Manipulation (SQL/Python) domain, focusing on practical application of SQL aggregation rather than purely conceptual theory.
Data Manipulation (SQL/Python)Online Assessment - ImcHardSoftware EngineerChoose container set to minimize waste
An IMC software engineer take-home asking you to pick the single container set that fulfills all medicine orders with minimum total waste. It tests ceiling-style binary search, per-set validity checks, smallest-index tie-breaking, and efficient handling of inputs up to 10^5 to avoid an O(n*T) timeout.
Coding & AlgorithmsOnline Assessment - ImcMediumSoftware EngineerFind k-th recipient in command propagation order
This question evaluates understanding of tree traversals, subtree indexing, and order-statistics on rooted trees, focusing on DFS-preorder propagation when children are visited in ascending id.
Coding & AlgorithmsOnline Assessment - InstacartMediumSoftware EngineerAdd Backend Search and Filters to the Items API of a Library Lending System
Implement and test backend search, multi-attribute filtering, sorting, and pagination logic for a library lending system's items catalog.
Software Engineering FundamentalsOnline AssessmentAPI DesignData FilteringPagination - InstacartMediumSoftware EngineerAdd Hold-Available and Loan Due-Date Notifications to a Library Lending System
Tests domain modeling, queue management, and idempotent notification triggering for an event- and time-driven library lending workflow.
Software Engineering FundamentalsOnline AssessmentObject-Oriented DesignState ManagementData Structures - InstacartMediumBackend EngineerDebug Metrics Computed Before Filtering
Debug a metrics endpoint whose summary is calculated before user filters are applied even though its rows are filtered correctly. Trace the data lineage, aggregate over the full matched population before pagination, preserve security scoping, and add unit and endpoint regression tests.
Software Engineering FundamentalsOnline Assessment - InstacartEasySoftware EngineerDebug Search and Stock Behavior in a Library Application
Debug a library application’s incomplete search and stock displays by reproducing symptoms, tracing API behavior, checking query semantics, and validating focused fixes.
Software Engineering FundamentalsOnline Assessment
HubSpot
Hudson River Trading
IBM
Imc
Instacart