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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
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- 11
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- 8
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Showing 7411–7440 of 9403 results
- RobloxHardData ScientistCompute DID estimate and pretrend flag
This Analytics & Experimentation question evaluates basic causal-inference and data-manipulation skills by requiring computation of a difference-in-differences (DID) estimate and a binary pretrend flag from panel-like arrays, at an implementation-level focused on summary statistics and edge-case handling.
Analytics & ExperimentationOnline Assessment - RobloxEasyData ScientistCompute diff-in-diff and pretrend flag
This question tests the ability to calculate a difference-in-differences (DiD) estimator for causal inference and implement a basic statistical test for pre-intervention trend divergence.
Analytics & ExperimentationOnline AssessmentCausal InferenceData WranglingStatistics - RobloxHardData ScientistCompute minimum sample size for A/B test
Evaluates the ability to perform sample size and power calculations for a two-sample z-test—including estimating outcome standard deviation from historical continuous data—and is categorized under Analytics & Experimentation for a Data Scientist role at an implementation-level applied statistics abstraction.
Analytics & ExperimentationOnline Assessment - RobloxHardData ScientistCompute sample size and Bayes posterior
This question evaluates understanding of statistical inference and probabilistic reasoning by combining a frequentist power/sample-size computation for a two-sided two-sample z-test with a basic Bayesian conditional probability calculation.
Statistics & MathOnline Assessment - RobloxHardSoftware EngineerCount Distinct Hat Assignments and Maximize Hat Points
Count valid one-hat-per-person assignments and maximize assigned-hat points with exact counts, unique hat use, and bitmask or backtracking reasoning.
Coding & AlgorithmsOnsite - RobloxMediumSoftware EngineerData Center Rack Units: Can a Centered Equipment Bay Be Reserved?
Process an online stream of rack-unit reservations and span-availability checks over an infinite 1D coordinate line, answering each availability check with the data seen so far.
Coding & AlgorithmsOnline Assessmentbinary-searchonline-queriesarrays - RobloxMediumData ScientistDefend a metric choice under scrutiny
This question evaluates a Data Scientist's competency in metric selection, stakeholder communication, and experiment governance when defending a non-obvious primary metric.
Behavioral & LeadershipOnsite - RobloxHardSoftware EngineerDefine success metrics and monitoring
Define success metrics and monitoring evaluates metric design, causal reasoning, experiment setup, diagnostics, SQL/statistical checks, and recommendations in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Analytics & ExperimentationOnsite - RobloxHardData ScientistDemonstrate fit with quantified stories and motivations
This question evaluates a Data Scientist's behavioral and leadership competencies, including storytelling with quantified impact, ownership of technical decisions, trade-off analysis, error detection and correction, motivation, team collaboration, and end-to-end project thinking.
Behavioral & LeadershipTechnical Screen - RobloxMediumData ScientistDerive variance and CTR confidence intervals
This problem tests your understanding of statistical inference for binomial proportions, specifically calculating confidence intervals for Click-Through Rates (CTR) and understanding how to aggregate variability across multiple days.
Statistics & MathTechnical ScreenStatisticsInferenceCTR - RobloxMediumData ScientistDescribe leading an ambiguous ads project
This question evaluates a data scientist's end-to-end ownership, experimental and analytics skills in ads/growth contexts, including hypothesis formulation, metric and guardrail selection, trade-off reasoning, stakeholder alignment, conflict resolution, and quantifying impact.
Behavioral & LeadershipTechnical Screen - RobloxHardData ScientistDescribe resolving revenue–UX metric conflict
This question evaluates a data scientist's competency in metrics-driven product leadership, focusing on balancing monetization and user-experience metrics, quantitative trade-off analysis, experiment design, risk management, and cross-functional stakeholder decision-making.
Behavioral & LeadershipTechnical Screen - RobloxEasySoftware EngineerDesign Multi-Dimensional Request Rate Limiting
Design a distributed, low-latency rate limiting service capable of enforcing multi-dimensional limits (e.g., by user ID, IP address, and endpoint) across a large-scale gaming platform.
System DesignTechnical ScreenDistributed SystemsRate LimitingCaching - RobloxMediumMachine Learning EngineerDesign a Game Recommendation System
This problem tests your ability to design a multi-stage recommendation architecture tailored to a gaming platform, focusing on user-specific constraints like age-appropriateness and the challenges of the long-tail game distribution.
ML System DesignOnsiteRecommendation SystemsSystem DesignRanking - RobloxHardSoftware EngineerDesign a Played-By Summary System
Design a scalable social-proof service that tracks unique player counts per experience and computes real-time friend-intersection summaries under high write throughput and low read latency.
System DesignTechnical Screensystem-designdistributed-systemscaching - RobloxMediumSoftware EngineerDesign a Real-Time Shared To-Do List
Design a real-time collaborative to-do list supporting concurrent edits, task reordering, fast write confirmations, and seamless reconnect recovery.
System DesignTechnical ScreenReal-TimeWebSocketsDistributed Systems - RobloxMediumFrontend EngineerDesign a Reusable Dropdown Menu Component
Tests a candidate's ability to architect a production-grade, reusable UI component library element with consideration for flexible API design, accessibility (WAI-ARIA), state management, and large dataset performance.
System DesignOnsiteFrontend System DesignReactAccessibility - RobloxMediumSoftware EngineerDesign a Scalable Like Counter
This question tests the ability to design a high-throughput, eventually consistent counting system that handles massive concurrent write volumes while maintaining low-latency read access.
System DesignOnsiteScalabilityDistributed SystemsCaching - RobloxMediumSoftware EngineerDesign a Scalable Likes System
This question tests your ability to design a high-throughput, distributed service for tracking user engagement, focusing on write-heavy loads and read-consistency trade-offs.
System DesignTechnical ScreenScalabilityDistributed SystemsCaching - RobloxHardSoftware EngineerDesign a Static Audio Detection System
This question evaluates system design and ML integration skills for building a scalable, reliable offline audio detection pipeline, including ingestion, preprocessing, STT and spectral feature extraction, rule-based post-processing, artifact persistence, and human-in-the-loop review within the ML system design domain.
ML System DesignOnsite - RobloxMediumMachine Learning EngineerDesign a game genre classifier
This question assesses the ability to design an end-to-end multi-modal machine learning system for classifying user-generated game content based on diverse input features and real-time serving requirements.
ML System DesignOnsiteMulti-modalNLPComputer Vision - RobloxEasySoftware EngineerDesign a game recommendation modeling approach
This problem tests the ability to design an end-to-end recommendation engine for a massive-scale gaming platform, focusing on user-item interaction modeling and handling cold-start scenarios.
ML System DesignTechnical ScreenRecommender SystemsML DesignRetrieval - RobloxMediumSoftware EngineerDesign a rate limiter
This problem tests your ability to design a distributed rate-limiting service that maintains request counts across multiple application nodes while balancing system performance and accuracy.
System DesignTechnical ScreenScalabilityDistributed SystemsCaching - RobloxHardMachine Learning EngineerDesign a real-time game recommendation system
Design a real-time game recommendation system 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 - RobloxHardSoftware EngineerDesign a scheduled payment system
This question evaluates proficiency in designing a reliable, scalable scheduled payment service, testing competencies in distributed systems, API design, scheduling and execution workflows, idempotency and deduplication, time semantics, transactional consistency, security and compliance, and operational monitoring.
System DesignOnsite - RobloxMediumSoftware EngineerDesign an In-App Notification Center with Real-Time Updates and Unread Counts
A system design question about an in-app notification center that turns product events into per-user notifications, shows an unread badge and a recent list, and pushes new items to online users. It tests fan-out strategy, inbox data modeling, unread counts, real-time delivery, reliability, and client design.
System DesignOnsite - RobloxHardData ScientistDesign experiment for homepage tab replacement
This question evaluates experiment design and causal-inference competency for product changes that impact both end users and platform creators, covering randomization strategies, metric and guardrail selection, power calculations, and handling of novelty, navigation friction, and ecosystem interference.
Analytics & ExperimentationTechnical Screen - RobloxMediumSoftware EngineerDesign favorites and social game recommendations
This question tests the ability to design a scalable, low-latency system for managing user-specific lists (favorites) and integrating real-time social signals into a game recommendation engine.
System DesignOnsiteScalabilityCachingSocial Graphs - RobloxMediumSoftware EngineerDesign in-game payment wallet system
Design in-game payment wallet system 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 - RobloxHardData ScientistDesign leakage-free predictive maintenance pipeline
This question evaluates a data scientist's competency in designing time-series predictive maintenance pipelines, focusing on temporal feature engineering, leakage prevention and point-in-time joins, handling late-arriving labels, class imbalance and cost-sensitive thresholding, probabilistic calibration, explainability, and operational drift monitoring. It is commonly asked in the Machine Learning domain to assess an applicant's ability to produce an end-to-end, production-ready workflow that balances practical implementation concerns with conceptual system-design reasoning, so the task is primarily practical application with important conceptual elements.
Machine LearningOnline Assessment
Roblox