practice a little every day, paws crossed ♡
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 3541–3570 of 4616 results
- 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 - 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 - 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 - 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 - 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 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 - RobloxMediumSoftware EngineerDiscovering a Design Flaw Right Before a Project Deadline: How Do You Respond?
A situational behavioral question for software engineers: your project is close to its deadline when you discover that an earlier design decision is flawed. It tests how you size the flaw's impact, weigh delaying against shipping with a mitigation or cutting scope, communicate with the people who own the date, and follow through.
Behavioral & LeadershipTechnical Screen - RobloxMediumData ScientistEvaluate Impact of New Roblox Homepage Tab
Roblox data scientist experimentation prompt on evaluating a new homepage tab, including hypotheses, engagement funnel metrics, guardrails, power, duration, segmentation, cannibalization, and rollout criteria.
Analytics & ExperimentationTechnical Screen - RobloxEasyMachine Learning EngineerExtend counter to per-client rate limiting
This question evaluates competency in designing per-client, time-windowed rate limiting using efficient data structures for time-based eviction and counting within the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - RobloxMediumSoftware EngineerFind largest digit-sum bucket size
This question evaluates a candidate's competency in combinatorial counting, digit-sum properties, and algorithmic optimization for range queries within the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - RobloxEasyData ScientistFind maximum follow depth using recursion
This question evaluates a candidate's competency with recursion, directed graph traversal, cycle detection, and memoization when computing longest-path depths in social-network-style follow graphs.
Coding & AlgorithmsTechnical Screen - RobloxMediumSoftware EngineerFind most frequent call path in logs
This problem tests your ability to parse structured log strings representing nested function calls into a hierarchical tree and identify the most frequently occurring execution path.
Coding & AlgorithmsTechnical ScreenStackHash MapString Manipulation - RobloxEasyMachine Learning EngineerFind the Most Frequent Log Call
This question evaluates a candidate's ability to perform frequency analysis on sequences, demonstrating competency with data structures for counting occurrences and with algorithmic time and space complexity considerations.
Coding & AlgorithmsTechnical Screen - RobloxMediumSoftware EngineerHandle Difficult Feedback and Manager Disagreement
Tests emotional intelligence, professional maturity, constructive disagreement, and the ability to accept critical feedback and commit to collective team decisions.
Behavioral & LeadershipTechnical Screenbehavioralleadershipconflict-resolution - RobloxMediumData ScientistImplement Python Function for Statistical Test P-Values
This question evaluates proficiency in statistical hypothesis testing, p-value interpretation, and implementing distribution-based calculations (Z and Student-t) in code, and it falls under the Coding & Algorithms domain for data scientist roles.
Coding & AlgorithmsTechnical Screen - RobloxMediumSoftware EngineerImplement Sliding-Window Rate Limiter
This problem tests your ability to implement a thread-safe rate limiter using a sliding window algorithm to ensure a user does not exceed a fixed number of requests within a rolling time frame.
Coding & AlgorithmsTechnical ScreenAlgorithmsData StructuresRate Limiting - RobloxMediumSoftware EngineerImplement a Rolling-Window Rate Limiter
Implement an in-memory, rolling-window rate limiter supporting per-client limits, precise boundary expiration, and stale state cleanup.
Software Engineering FundamentalsTechnical ScreenData StructuresQueueSystem Design - RobloxEasyMachine Learning EngineerImplement recent-requests counter
This question evaluates a candidate's ability to design efficient in-memory data structures and manage time-windowed event counting, testing algorithmic reasoning and performance optimization for high-throughput services.
Coding & AlgorithmsTechnical Screen - RobloxHardData ScientistImplement robust one/two-sided p-value function
This question evaluates proficiency in statistical hypothesis testing, numerical computing, and numerical stability when implementing p-value calculations for z and t distributions, and it targets the Statistics & Math domain for a data scientist role.
Statistics & MathTechnical Screen - RobloxMediumData ScientistImplement streaming CTR with deduplication
This question evaluates streaming data-processing and algorithmic design skills, specifically time-windowed aggregation, click deduplication, late-event handling, state management, and selection of data structures for per-campaign CTR computation.
Coding & AlgorithmsTechnical Screen - RobloxMediumMachine Learning EngineerLevel-Ordered Dependency Build Order
This problem tests your ability to perform a Kahn’s algorithm-based topological sort while grouping tasks into parallelizable layers, ensuring cycle detection and dependency validation.
Coding & AlgorithmsTechnical ScreenGraphBFSTopological Sort - RobloxMediumSoftware EngineerMatch-3 Grid: Find Horizontal and Vertical Runs, Then Clear and Drop Cells
A two-part grid problem modeled on a Match-3 game: report every horizontal and vertical run of three or more equal values in a fixed scan order, then clear the matched cells and let the remaining values in each column fall to the bottom. It tests precise run detection, ordering rules and grid simulation.
Coding & AlgorithmsTechnical Screen - RobloxMediumData ScientistMeasure Success for a New Chat System
Build a chat-system launch framework with meaningful communication metrics, reliability and safety guardrails, and experiments that address network effects.
Analytics & ExperimentationTechnical Screen - RobloxMediumSoftware EngineerRandomly partition array into k segments
This question evaluates algorithm design, randomization techniques, and time/space complexity analysis within the Coding & Algorithms domain, focusing on partitioning an array into random non-empty segments.
Coding & AlgorithmsTechnical Screen
Roblox