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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
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- 546
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- 11
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- 8
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Showing 181–210 of 781 results
- Capital OneMediumData ScientistCompute and interpret 95% confidence intervals
This question evaluates proficiency with confidence intervals, hypothesis testing for proportions and means, multiple-comparison adjustment (Bonferroni), and sample size calculations, including assessment of normal-approximation versus Wilson score methods.
Statistics & MathOnline Assessment - Capital OneHardMachine Learning EngineerCompute minutes since last train departure
This problem tests your ability to manipulate time objects, handle cyclic day-wrap scenarios, and perform efficient searching on sorted lists.
Coding & AlgorithmsOnline AssessmentArraysSortingTime Complexity - Capital OneMediumSoftware EngineerCount Pairs of Cyclically Equivalent Integers
This problem tests your ability to normalize strings under cyclic rotation using hashing or canonical representation, combined with frequency counting to efficiently identify equivalent pairs.
Coding & AlgorithmsOnline AssessmentHashingStringsCombinatorics - Capital OneMediumSoftware EngineerCount Pairs of Points Within 2 Units on Both Axes
A coding question that asks how many pairs of points intersect, where two points intersect when both their x-coordinates and their y-coordinates differ by at most 2. It tests counting unordered pairs with duplicate points, inclusive bounds and scaling to 100,000 points with large coordinates.
Coding & AlgorithmsOnline Assessment - Capital OneHardSoftware EngineerCount Subarrays Containing at Least k Disjoint Pairs of Equal Values
Count the contiguous segments of an integer array, framed as fruit types on a conveyor belt, that contain at least k pairs of equal values with no position used in two pairs. Tests reasoning about how the number of disjoint pairs changes as a segment grows, and efficient counting on inputs of up to 100,000 elements.
Coding & AlgorithmsOnline Assessment - Capital OneMediumSoftware EngineerCount Subarrays Whose Step-by-Step Changes Match an Up, Flat, Down Pattern
Count the fixed-length windows of an integer array whose consecutive rises, equal steps, and drops follow a given pattern of 1, 0, and -1 values, counting overlapping matches separately. Tests turning a comparison rule into an exact window check with correct index bounds.
Coding & AlgorithmsOnline Assessment - Capital OneMediumSoftware EngineerCount Three-Digit Numbers With All-Distinct Digits in a Range
A coding question that asks you to count the three-digit integers in an inclusive range whose hundreds, tens and units digits are all different from one another. It tests digit extraction, inclusive range boundaries and treating zero digits like any other digit.
Coding & AlgorithmsOnline Assessment - Capital OneMediumSoftware EngineerCount Windows That Follow an Increase, Equal, Decrease Pattern
A coding question that gives an integer array and a pattern of 1, 0 and -1 values standing for an increase, an equal step and a decrease, and asks how many windows of consecutive elements follow the pattern exactly. It tests translating pairwise comparisons into steps and counting overlapping matches efficiently.
Coding & AlgorithmsOnline Assessment - Capital OneMediumSoftware EngineerCount ordered pairs that concatenate to target
This question evaluates a candidate's ability to manipulate string and numeric representations, perform efficient counting, and leverage associative data structures to identify matching concatenations.
Coding & AlgorithmsOnline Assessment - Capital OneMediumMachine Learning EngineerDescribe projects, conflicts, and tough stakeholders
This question evaluates project ownership, technical troubleshooting, cross-team communication, conflict resolution, and stakeholder management competencies for a Machine Learning Engineer within the Behavioral & Leadership domain.
Behavioral & LeadershipOnline Assessment - Capital OneMediumSoftware EngineerDesign Nearest-Pickup Search with Time
Design efficient nearest-pickup search for latitude-longitude data and a time-aware extension while clarifying distance, ties, result order, and temporal ranking.
Software Engineering FundamentalsOnline Assessment - Capital OneHardData ScientistDesign and analyze ad A/B test
This question evaluates a candidate's competency in online experimentation and statistical analysis, covering hypothesis formulation, variance reduction, clustering and stratification, multiplicity control, power/MDE calculation, and operational metric guardrails.
Analytics & ExperimentationOnline Assessment - Capital OneHardData ScientistDesign and analyze ads A/B test this week
This question evaluates experimental design and applied statistical analysis skills for A/B testing, covering randomization, exposure control, stratification, variance reduction methods, metric formalization, hypothesis testing, sample sizing, sequential monitoring, diagnostics, and handling delayed offline conversions.
Analytics & ExperimentationOnline Assessment - Capital OneMediumSoftware EngineerFind Repeated-Value Patterns in a Matrix
Match a symbol pattern inside an integer matrix using per-window bijections, repeated values, distinct symbols, and ordered match coordinates.
Coding & AlgorithmsOnline Assessment - Capital OneMediumSoftware EngineerFind the First Array Element Smaller Than Both of Its Neighbors
A coding problem that asks for the first element of an integer array whose left and right neighbors are both strictly larger than it, returning -1 when no element qualifies. It tests careful boundary handling, strict comparisons when neighbors are equal, and precise output rules.
Coding & AlgorithmsOnline Assessment - Capital OneMediumSoftware EngineerFind the Row Watched by the Most Security Cameras
Each security camera covers a symmetric band of rows around its mounted position; find the integer row watched by the most cameras, breaking ties toward the smallest row number, using a sweep-line count instead of scanning every covered row.
Coding & AlgorithmsOnline Assessmentsweep-linesortingintervals - Capital OneMediumSoftware EngineerFind the Top-Left Submatrix Matching a Grid Pattern With Letter Variables
Locate a pattern grid inside an integer matrix, where each pattern cell is either an exact number or a letter that must stand for one consistent value, and return the top-left corner of the match with the lowest row and then the lowest column. It tests two-dimensional scanning, variable binding, and tie-breaking rules.
Coding & AlgorithmsOnline Assessment - Capital OneMediumData ScientistFind top category per region in Aug 2025
This question evaluates proficiency in SQL data manipulation skills such as joining related tables, aggregating revenue, filtering by date and status, and implementing deterministic tie-breaking for categories.
Data Manipulation (SQL/Python)Online Assessment - Capital OneMediumData ScientistFix dash dates and aggregate watch time
This question evaluates data-cleaning and aggregation competencies, focusing on handling nonstandard missing-date markers, forward-filling in spreadsheets, correct date-range filtering, pivot-table summarization, and concise pandas grouping and aggregation.
Data Manipulation (SQL/Python)Online Assessment - Capital OneMediumSoftware EngineerImplement 2D transforms and find max-lit point
This question evaluates array-manipulation and interval-analysis skills, specifically in-place 2D matrix transformations (row/column swaps, reversals, rotations) and determining the point with maximum overlap among one-dimensional illumination intervals.
Coding & AlgorithmsOnline Assessment - Capital OneMediumMachine Learning EngineerImplement string/matrix simulations and counting pairs
This problem tests string manipulation, simulation of grid-based gravitational collapse, and efficient combinatorial counting of string combinations.
Coding & AlgorithmsOnline AssessmentStringsSimulationHashing - Capital OneMediumData ScientistMerge CSVs and build revenue pivot with pandas
This question evaluates proficiency in data manipulation and ETL using pandas, covering robust file I/O, join/merge semantics, null/coalescing behavior, date parsing, aggregation, and pivoting.
Data Manipulation (SQL/Python)Online Assessment - Capital OneMediumData ScientistMerge ad CSVs and compute CTR
This question evaluates SQL data manipulation competencies such as cleaning and merging CSVs, forward-filling missing dates, correct multi-table joins without duplication, use of window functions, time-windowed aggregations, and computation of click-through rate (CTR).
Data Manipulation (SQL/Python)Online Assessment - Capital OneHardSoftware EngineerReorder a String by Alternating Its Front and Back Characters
Rearrange a string by taking characters alternately from its front and its back: first, last, second, second-to-last and so on until every character is used once. Tests clean index handling for even and odd lengths and building the result efficiently for long inputs.
Coding & AlgorithmsOnline Assessment - Capital OneMediumSoftware EngineerReorder a String by Alternating Its Left and Right Ends
This problem tests string manipulation, two-pointer logic, and the ability to efficiently manage index traversal in both directions simultaneously.
Coding & AlgorithmsOnline AssessmentTwo PointersStringsAlgorithms - Capital OneMediumData ScientistResolve a Mismatch Between Regression and Classification Metrics
Tests your ability to diagnose modeling and metric mismatches in credit risk and fraud scenarios, design proper two-stage architectures, and select evaluation metrics aligned with business decisions.
Machine LearningOnline Assessmentmachine-learningmodel-evaluationregression - Capital OneMediumSoftware EngineerReturn the Top Two Teams by Points, Goal Difference, and Tie Breakers
Implement a ranking algorithm to evaluate sports competition matches, compute points, goal differential, and total goals for each team, and return the indices of the top two teams using multi-level tie-breakers.
Coding & AlgorithmsOnline AssessmentSortingHash TableArray - Capital OneMediumMachine Learning EngineerRotate matrix and find max lamp coverage
This question evaluates array and matrix manipulation, in-place algorithm design, interval processing (sweep-line) and interval merging skills, testing competencies in algorithm design, complexity analysis, and robust edge-case reasoning within the Coding & Algorithms domain.
Coding & AlgorithmsOnline Assessment - Capital OneMediumSoftware EngineerSimulate Rot Spreading Through an Orchard Grid Over a Number of Days
A grid simulation question about an orchard of rotten trees, healthy trees and empty ground, where each day rot spreads at once from every rotten tree to the healthy trees directly beside it. It asks for the orchard after a given number of days and tests simultaneous updates, blocked cells and very large day counts.
Coding & AlgorithmsOnline Assessment - Capital OneMediumMachine Learning EngineerSimulate round-robin package assignment to servers
This problem tests array indexing manipulation and logic for stateful resource allocation, specifically handling circular queues with dynamic availability constraints.
Coding & AlgorithmsOnline AssessmentArraysSimulationQueueing
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