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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 3241–3270 of 4616 results
- PinduoduoMediumSoftware EngineerGenerate a Matrix in Spiral Order
This problem tests your ability to simulate a specific traversal pattern in a 2D grid and maintain precise boundary pointers to fill the matrix correctly.
Coding & AlgorithmsTechnical ScreenArrayMatrixSimulation - PinduoduoEasySoftware EngineerGenerate a Spiral Matrix
This problem tests your ability to manage matrix traversal coordinates and maintain state (direction and boundaries) while iteratively filling a grid.
Coding & AlgorithmsTechnical ScreenArraysMatricesSimulation - PinduoduoMediumSoftware EngineerLongest Single-Letter Substring After at Most k Character Changes
Given a string of uppercase letters and a budget of at most k single-character changes, find the longest run of one repeated letter that can be produced. Tests reasoning about which substrings can be made uniform, efficient counting, and a near-linear solution for strings of up to 100,000 characters.
Coding & AlgorithmsTechnical Screen - PinduoduoMediumSoftware EngineerNavigate a Senior Engineering HR Interview
Build a consistent narrative for a senior engineering HR interview covering current scope, motivation, role interest, parallel processes, and compensation. Ground seniority in evidence, protect confidential information, and compare opportunities using total compensation and role fit.
Behavioral & LeadershipTechnical Screen - PinduoduoHardSoftware EngineerPresent Evidence for Professional Strengths and Weaknesses
This question assesses the candidate's self-awareness, ability to reflect on professional growth, and capacity to articulate impact through specific, evidence-based storytelling.
Behavioral & LeadershipTechnical ScreenBehavioralSelf-ReflectionSoft Skills - PinduoduoMediumSoftware EngineerTrace Java Static and Instance Field Initialization
This question tests the understanding of Java class loading, static initialization blocks, and the order of operations between class-level and instance-level fields.
Software Engineering FundamentalsTechnical ScreenJavaJVMStatic-Initialization - PinduoduoMediumSoftware EngineerTraverse a Matrix in Spiral Order
Traverse a rectangular matrix in clockwise spiral order using shrinking boundaries. Handle empty, single-row, and single-column inputs without duplicates while achieving linear time and constant auxiliary space beyond the result.
Coding & AlgorithmsTechnical Screen - PinterestMediumSoftware EngineerAnswer Policy Violation Log Queries
Design an in-memory query engine over a timestamp-sorted policy violation log to support aggregate, point, and range queries efficiently using hash maps and binary search.
Coding & AlgorithmsTechnical Screenhash-tablebinary-searchdesign - PinterestMediumSoftware EngineerAssign Pins to Shortest Columns
This question evaluates understanding of greedy assignment strategies and data structures for maintaining and updating minimums in an online allocation problem, while also testing load-balancing reasoning and analysis of time and space complexity.
Coding & AlgorithmsTechnical Screen - PinterestHardMachine Learning EngineerBias-Variance Tradeoff and Vanishing Gradients in Feedforward Networks
Tests theoretical and mathematical understanding of the bias-variance decomposition and the vanishing-gradient phenomenon during backpropagation in deep feedforward architectures.
Machine LearningTechnical ScreenDeep LearningBackpropagationModel Generalization - PinterestMediumData ScientistCalculate the Percentage of Highly Active Users by Country
Calculate highly active users by country over seven calendar days using distinct active dates and same-day surface diversity, with percentage output.
Data Manipulation (SQL/Python)Technical Screen - PinterestMediumData ScientistCompute CTR by format for new US users
This question evaluates a candidate's competency in SQL data manipulation and aggregation, covering joins, date-based filtering for user cohorts, deduplication, conditional summing, null-safe arithmetic, rounding, and ordering to compute a business metric (CTR).
Data Manipulation (SQL/Python)Technical Screen - PinterestEasyData ScientistCompute average unique pins per user
This question evaluates a candidate's ability to process collections and compute aggregated metrics, including per-user deduplication of items, handling of missing/null entries, numeric averaging and rounding.
Coding & AlgorithmsTechnical Screen - PinterestEasyData AnalystCompute percent of first-cancel users who never return
This question evaluates a candidate's competency in data manipulation and temporal analysis using SQL/Python, focusing on computing user-level metrics and correctly ordering time-based events.
Data Manipulation (SQL/Python)Technical Screen - PinterestMediumData AnalystCompute percent of first-cancelled users who never rebook
This question evaluates proficiency in SQL data manipulation—specifically use of window functions, CTEs, deduplication by earliest timestamp, temporal comparisons, and cohort-level aggregation—within the Data Manipulation (SQL/Python) domain for a Data Analyst role in health‑tech product analytics.
Data Manipulation (SQL/Python)Technical Screen - PinterestMediumSoftware EngineerDecide target via subsequence plus/multiply expression
A Pinterest software-engineer coding screen: given positive 32-bit integers and a target, decide whether some subsequence with '+'/'*' operators evaluated strictly left to right (equal precedence) hits the target, and return a valid expression. The answer spans forward backtracking, monotonicity-based pruning, a divisibility-guided reverse search from the target, complexity analysis, and 32-bit overflow handling.
Coding & AlgorithmsTechnical Screen - PinterestMediumSoftware EngineerDelete and Compact a Forest Stored by Parent Indices
Implement subtree deletion on a parent-pointer forest array, supporting tombstoning and index compaction with pointer remapping.
Coding & AlgorithmsTechnical Screentreegrapharray - PinterestMediumSoftware EngineerDesign Blackjack Hands, Splits, and a Multi-Deck Shoe
This problem tests object-oriented design principles, specifically the ability to model a card game with multiple decks, complex state transitions (like splitting), and encapsulation of game rules.
Software Engineering FundamentalsTechnical ScreenObject-Oriented DesignSystem ModelingGame Logic - PinterestMediumMachine Learning EngineerDesign Hierarchical Permission Checks
This question evaluates understanding of hierarchical access control, tree data structures, and permission inheritance, testing competencies in data modeling and algorithmic reasoning.
Coding & AlgorithmsTechnical Screen - PinterestMediumSoftware EngineerDesign a Distributed Rate Limiter
This problem evaluates your ability to design a distributed rate-limiting service that maintains low latency while enforcing consistent request quotas across multiple global nodes.
System DesignTechnical ScreenDistributed SystemsCachingConcurrency - PinterestMediumSoftware EngineerDesign a violation log analyzer
This question evaluates proficiency in data structures, in-memory indexing and query design, algorithmic time/space complexity analysis, and reasoning about state management for dynamic event streams.
Coding & AlgorithmsTechnical Screen - PinterestHardMachine Learning EngineerDesign an ads system to improve CTR
This question evaluates machine learning system design competency for improving ad click-through rate, testing understanding of metrics, end-to-end architecture, training data and embeddings, and operational issues like cold start, bias and delayed feedback within advertising and recommender domains.
ML System DesignTechnical Screen - PinterestMediumData ScientistDesign and Evaluate a Home Carousel
This question evaluates a candidate's expertise in product analytics, experimentation design, metric definition, and instrumentation for measuring the impact of a new UI feature.
Analytics & ExperimentationTechnical Screen - PinterestHardData ScientistDesign and Interpret a Video Pin Experiment
This question tests the ability to design a balanced A/B experiment for a two-sided marketplace (creators and viewers) and synthesize conflicting metrics into a launch decision.
Analytics & ExperimentationTechnical ScreenA/B TestingProduct MetricsGuardrails - PinterestMediumData ScientistDesign and assess a video-pin increase experiment
A Pinterest Data Scientist technical-screen question on Analytics & Experimentation: design a rigorous A/B test for increasing video-pin share in the Home Feed — unit of randomization, primary metric and guardrails, power/MDE, sequential analysis, and a quasi-experiment fallback — then interpret two 14-day readouts and recommend ship, iterate, or stop. It rewards balancing engagement lifts (CTR) against guardrail regressions (retention, complaints, crash rate), multiple-testing robustness, and cross-unit (per-impression vs per-session) trade-offs.
Analytics & ExperimentationTechnical Screen - PinterestHardData ScientistDesign metrics and experiment for Shopping launch
This question evaluates a data scientist’s competency in experimental design and product analytics, including metric selection and precise definitions, guardrail and funnel diagnostics, spillover and novelty handling, power/MDE estimation, and multi-objective decision framing.
Analytics & ExperimentationTechnical Screen - PinterestMediumSoftware EngineerDetermine equality of arbitrarily nested sets
This question evaluates understanding of nested data structures and set semantics, including canonicalization, hashing, recursion, handling of edge cases, unit-test design, and time/space complexity analysis.
Coding & AlgorithmsTechnical Screen - PinterestMediumData ScientistEvaluate Carousel and Billboard Lift
This question tests your ability to design an A/B test for multi-format advertising, specifically handling cannibalization and cross-format lift measurement.
Analytics & ExperimentationTechnical ScreenA/B TestingCausal InferenceMetrics - PinterestMediumData ScientistEvaluate Fresh Content and Video Experiments
This question evaluates competencies in metric design, experimental design, statistical inference, and product analytics—specifically defining and critiquing freshness metrics, formulating null and alternative hypotheses for content changes, interpreting A/B test results, and calculating sample size and power.
Analytics & ExperimentationTechnical Screen - PinterestMediumMachine Learning EngineerExplain bias–variance, overfitting, and vanishing gradients
This question tests the conceptual understanding of the bias-variance tradeoff, methods for diagnosing and preventing overfitting, and the theoretical causes and architectural solutions for vanishing gradients in deep learning.
Machine LearningTechnical ScreenDeep LearningBias-Variance TradeoffRegularization
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