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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
- Topics
- 8
- Languages
Showing 2281–2310 of 4616 results
- MercorMediumSoftware EngineerExplain what happens when opening a website
This question evaluates understanding of the end-to-end web request lifecycle, including DNS resolution, TCP/TLS handshakes, HTTP(S) exchanges, CDN and load balancer behavior, server-side handling, and the browser rendering pipeline.
Software Engineering FundamentalsTechnical Screen - MercorHardSoftware EngineerFind the Probability That One Shop Supplies the Top Two Coffees
Calculate the probability that the top-ranked coffees in a blind competition come from the same shop under an exchangeable, tie-free ranking model.
Statistics & MathTechnical Screenprobabilitycombinatoricsexchangeability - MercorMediumSoftware EngineerFind the Production Bugs in a Dictionary Cache Around an Expensive Computation
Review a short Python function that caches the results of an expensive computation in a dictionary, and identify what breaks in a long-running, concurrent production service. Tests reasoning about memory growth, eviction policy, concurrent cache misses, error handling, and input validation.
Software Engineering FundamentalsTechnical Screen - MercorMediumSoftware EngineerMake a Charge-Then-Record Payment Endpoint Safe Against Timeouts, Retries and Crashes
A payment endpoint calls an external provider to charge the customer and then writes a record to its own database. The question asks what can go wrong and how to redesign the flow, testing failure analysis for crashes and timeouts, safe retries, durable payment state, recovery through status checks, webhooks and reconciliation, and lock placement.
System DesignTechnical Screen - MercorMediumSoftware EngineerMake a Dict-Based Memoization Cache Safe for Concurrent Threads
A memoization cache built on a plain Python dictionary wraps an expensive function and is now called from many threads at once. The question asks what goes wrong and how to fix it, testing race-condition analysis, lock scope and its throughput cost, duplicate-work prevention, and exception handling for waiting callers.
Software Engineering FundamentalsTechnical Screen - MercorMediumSoftware EngineerProbability Both Drinks from One Coffee Shop Outscore Both Drinks from Another
A probability brainteaser: two drinks are ordered at each of two coffee shops and every drink receives a quality score, and you must find the probability that both drinks from the first shop outscore both drinks from the second. It tests symmetry arguments, counting rankings, and stating independence and tie assumptions.
Statistics & MathTechnical Screen - MercorMediumSoftware EngineerProbability That One Customer's Two Coffees Beat Another's Two
A probability puzzle in which two customers each buy two cups of coffee of random quality, and you find the chance that one customer's cups are better than the other's. It tests clarifying what better means, using symmetry over rankings, checking the result a second way, and reasoning about ties and correlated cups.
Statistics & MathTechnical Screen - MercorMediumSoftware EngineerProject Deep Dive With Product-Level Probing, AI Tool Use, and Startup Motivation
A startup background round: introduce yourself, walk through a recent project probed from a product angle (who owns each decision, what done means, success metrics), explain what the company does and why you want to join, and describe your side project. It also tests how you use AI tools for on-call automation, code review, and design discussions.
Behavioral & LeadershipTechnical Screen - MercorMediumSoftware EngineerReason About Coffee-Quality Comparison Probabilities
Calculate conditional comparison probabilities for coffee quality scores under continuous and discrete distributions, accounting for ties and sample permutations.
Statistics & MathTechnical Screenprobabilitycombinatoricsstatistics - MercorMediumSoftware EngineerReview a Hand-Rolled Python CSV Serializer for Correctness and Performance Bugs
A code review question on a short Python function that turns a table of rows into CSV text. Candidates must find its correctness and performance problems and write a fixed version, which tests delimiter handling, string building in Python, non-string cells, CSV quoting and escaping rules, and how to verify the fix.
Software Engineering FundamentalsTechnical Screen - MercorHardSoftware EngineerReview an Asynchronous Cache for Races, Memory Growth, and Thread Safety
Tests understanding of asynchronous race conditions, memory leaks, and eviction in single-threaded event loops versus multithreaded synchronization in languages like C++.
Software Engineering FundamentalsTechnical ScreenConcurrencyAsync/AwaitCaching - MercorMediumSoftware EngineerShortest Grid Path with Obstacle Eliminations
This question tests your ability to apply Breadth-First Search (BFS) on an augmented state space where path state includes both coordinates and remaining resources.
Coding & AlgorithmsTechnical Screenbfsgraphmatrix - MercorMediumSoftware EngineerSorting Complexity: Beating O(n^2), Quicksort's Worst Case, and a Slower Sort
A verbal sorting-theory discussion: explain how to sort faster than quadratic insertion sort, identify quicksort's worst case, count the non-empty subsequences and the permutations of an n-element array, and design a correct sort that is deliberately slower than O(n^2). It tests asymptotic analysis, recurrence reasoning, and basic combinatorics.
Software Engineering FundamentalsTechnical Screen - MercorMediumSoftware EngineerStripe Payment Integration: Error Handling, Idempotent Retries and Payment Storage
Explain how to add a Stripe payment integration to a backend service: how to handle errors and retries without charging a customer twice, what payment data to store, and which database to use given ACID and availability needs. Tests idempotency, failure handling, and data modeling for payments.
Software Engineering FundamentalsTechnical Screen - MercorMediumSoftware EngineerThe Worst Possible Sorting Algorithm and How to Enumerate Every Permutation
A verbal algorithms question: name the worst sorting algorithm that still always sorts correctly, analyze its running time, and explain how you would compute every permutation of the input exactly once. It tests reasoning about factorial complexity and knowledge of permutation enumeration methods.
Software Engineering FundamentalsTechnical Screen - MergeMediumSoftware EngineerDesign a Common Data Class to Normalize Different API Responses
Design a common data class that can hold API responses describing the same kind of record but differing in field names, nesting, ID types and timestamp formats, plus the code that maps each response into it. It tests data modeling, normalization, handling of missing and extra fields, and how the records would be stored in a database.
Software Engineering FundamentalsTechnical Screen - MergeMediumSoftware EngineerOrg Chart from a Reporting List: Count Orgs, Print by Level, Find a Common Manager
Given a company's employees as (id, title, reports_to) tuples with heads reporting to None, count the separate orgs, print employees level by level, and find the first manager two employees share. It tests building a tree from manager pointers, level-order traversal, ancestor queries and edge cases under a tight time limit.
Software Engineering FundamentalsTechnical Screen - MetaMediumData ScientistAnalyze Bookstore Data to Identify Top Payment Methods
This question evaluates data manipulation and analytical SQL/Python competency, focusing on relational joins, aggregations, string filtering, ranking, and proportion calculations across multiple tables in a bookstore schema.
Data Manipulation (SQL/Python)Technical Screen - MetaMediumData ScientistAnalyze Mobile Promo Orders with SQL Query and Metrics
This question evaluates SQL data-manipulation and analytical competencies, including filtered joins, conditional aggregation, date-window filtering, and business-metric design to measure promotional performance on mobile orders.
Data Manipulation (SQL/Python)Technical Screen - MetaMediumData ScientistAnalyze Seller Activity and Vehicle Listing Interactions
This interview question evaluates SQL or pandas logic, joins, grouping, window functions, null handling, edge cases, and validation in a realistic interview setting. A strong answer for Analyze Seller Activity and Vehicle Listing Interactions states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Data Manipulation (SQL/Python)Technical Screen - MetaMediumData ScientistAnalyze Social Media Engagement with SQL Queries
This question evaluates SQL data-manipulation and analytics competencies, including aggregation, DISTINCT counting, joins between view and action logs, date-range filtering, and conditional metric computation from event data.
Data Manipulation (SQL/Python)Technical Screen - MetaMediumData ScientistAnalyze Top Call Initiators and Active French Video Callers
This question evaluates proficiency in SQL-based data manipulation and analytics—specifically aggregation, grouping, time-window filtering, and percentage calculations—by asking for the top call initiators over the last seven days and the proportion of active users in France on video calls yesterday, and is categorized under Data Manipulation (SQL/Python) for a Data Scientist role with a focus on practical application. It is commonly asked in technical interviews to assess a data scientist's ability to extract actionable engagement metrics from event logs, reason about temporal windows and population denominators, and produce accurate, explainable reporting from production-style datasets.
Data Manipulation (SQL/Python)Technical Screen - MetaMediumData ScientistAnalyze User Engagement and Spammer Read-Rate in SQL
This question evaluates SQL-based data manipulation and analytics skills—specifically joins, time-window filtering, aggregation, and metric calculation for measuring user engagement and spammer read-rate—within the Data Manipulation (SQL/Python) domain.
Data Manipulation (SQL/Python)Technical Screen - MetaMediumData ScientistAnalyzing abuse in the content‑reporting system
Evaluates reporting-system analytics for valid reports and misuse detection in moderation workflows. Strong answers define distinct reported-user share, write SQL for valid reports, and detect abusive reporters through frequency, hit-rate, burst, and coordination metrics.
Analytics & ExperimentationTechnical Screen - MetaMediumSoftware EngineerAnswer conflict, ambiguity, feedback, difficult coworker prompts
This question evaluates a candidate's ability to handle conflict with supervisors, clarify ambiguous requirements, provide constructive feedback and mentorship, and manage difficult collaborators.
Behavioral & LeadershipTechnical Screen - MetaMediumMachine Learning EngineerAnswer senior-level behavioral interview questions
This question evaluates leadership, decision-making, risk management, stakeholder management, and impact-communication skills for a senior Machine Learning Engineer role within the Behavioral & Leadership category.
Behavioral & LeadershipTechnical Screen - MetaMediumData ScientistAssess ranking change and design experiment
This question evaluates a candidate's competency in causal inference, experimentation design, metric definition, and observational analytics for product ranking and engagement problems within the Analytics & Experimentation domain for Data Scientist roles.
Analytics & ExperimentationTechnical Screen - MetaMediumData ScientistAssessing whether a new metric A is meaningful for News Feed
Evaluates whether a proposed News Feed proxy metric is meaningful for long-term user value. Strong answers test predictive power, actionability, gaming risk, true-outcome alignment, collection cost, privacy, latency, and decision criteria.
Analytics & ExperimentationTechnical Screen - MetaMediumSoftware EngineerBehavioral: Cross-Functional Disagreement and a Manager Conflict You Got Wrong
A senior behavioral question on conflict: describe a significant disagreement with a partner from another function and a conflict with your manager in which you turned out to be wrong. It tests how you raise disagreement, argue from evidence, change your mind gracefully and protect working relationships.
Behavioral & LeadershipTechnical Screen - MetaMediumSoftware EngineerBehavioral: Your Highest-Impact Project and an Innovation You Did Not Plan
A senior behavioral question pairing two prompts: walk through the most impactful project you have worked on, and a time you came up with an innovation you had not set out to create. It probes scope beyond your own team, ownership of ambiguous problems, measurable outcomes and what the experience changed in how you work.
Behavioral & LeadershipTechnical Screen
Mercor
Meta