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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
- Companies
- 11
- Topics
- 8
- Languages
Showing 2251–2280 of 4616 results
- LyftMediumData ScientistInvestigate Metric Drops and Coupon Retention
This question tests your ability to diagnose a sudden drop in a core business metric, distinguish between technical tracking issues and product-driven behavior, and design a strategy to evaluate coupon effectiveness.
Analytics & ExperimentationTechnical ScreenProduct AnalyticsExperimentationCausal Inference - LyftMediumData ScientistInvestigate Sudden Metric Changes and Design A/B Test
Investigate Sudden Metric Changes and Design A/B Test 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 & ExperimentationTechnical Screen - LyftMediumData ScientistInvestigate a 7% Monthly Active Riders Drop and a 20% Wait-Time Increase
Tests your ability to conduct a structured root-cause analysis on simultaneous marketplace metric regressions, decomposing supply-demand dynamics and separating correlation from causation.
Analytics & ExperimentationTechnical ScreenMarketplace AnalyticsRoot Cause AnalysisMetrics & KPIs - LyftMediumMachine Learning EngineerReason About an Intercept Shift in Logistic Regression
Tests understanding of how an additive shift to the intercept of a logistic regression model impacts predicted probabilities, ranking metrics (ROC-AUC), thresholded classification metrics (Recall, FPR, Precision), and calibration.
Machine LearningTechnical ScreenLogistic RegressionModel EvaluationClassification Metrics - LyftMediumSoftware EngineerSmallest Covering Window in a String
Tests using the two-pointer sliding window pattern combined with frequency counting to find the shortest substring satisfying multiset inclusion constraints in linear time.
Coding & AlgorithmsTechnical Screensliding-windowtwo-pointershash-table - LyftMediumMachine Learning EngineerTrain vs Test Error Diagnosis, Overfitting Fixes by Model Type, and Cross-Validation
A machine learning fundamentals screen that asks you to diagnose models from pairs of training and test error, including the unusual case where the test error is the lower one. It continues with curbing overfitting in linear, tree-based and neural network models, and with setting up validation splits and k-fold cross-validation.
Machine LearningTechnical Screen - MathWorksMediumSoftware EngineerDetermine Whether P's Position Is Unique
This question evaluates constraint-satisfaction and combinatorial search skills, specifically reasoning about spatial relations and whether a target's location is uniquely determined among all valid assignments on a discrete grid.
Coding & AlgorithmsTechnical Screen - MathWorksMediumSoftware EngineerExplain why EDG and why you fit
This question evaluates motivation, cultural alignment, communication skills, and the ability to present concrete, impact-driven examples from prior work, and it falls under the Behavioral & Leadership domain.
Behavioral & LeadershipTechnical Screen - MathWorksEasySoftware EngineerHow to maximize rewards with exactly k tasks
This Coding & Algorithms question evaluates a candidate's ability to perform combinatorial optimization and benefit-based assignment reasoning on arrays, testing algorithm design, complexity-aware implementation, and quantitative decision-making in constrained assignment problems.
Coding & AlgorithmsTechnical Screen - MathWorksEasySoftware EngineerMaximize minimum after K decrements
This Coding & Algorithms question evaluates algorithmic problem-solving skills in array manipulation and constrained optimization, testing competency in reasoning about value distribution, large numeric bounds, and performance under tight complexity limits.
Coding & AlgorithmsTechnical Screen - MathWorksEasySoftware EngineerMinimize shortest path by adding weight-1 edges
This question evaluates proficiency in graph algorithms, shortest-path computation, and algorithmic optimization when augmenting a directed weighted graph with additional unit-weight edges.
Coding & AlgorithmsTechnical Screen - MercorMediumSoftware EngineerBehavioral: The Project You Are Leading and Why You Are Its Owner
Describe the project you are currently leading, then defend why you are its owner rather than just a participant. The behavioral question tests whether you can explain a project crisply and back up a claim of ownership with specific decisions, risks you handled, accountability for setbacks and honest boundaries.
Behavioral & LeadershipTechnical Screen - MercorMediumMachine Learning EngineerBuild an Ollama Eval Harness
This question evaluates a candidate's ability to design and implement a lightweight evaluation harness for a locally hosted language model, testing competencies in ML system design, service integration, metrics instrumentation, reliability engineering (timeouts, retries), concurrency control, configuration management, and extensibility.
ML System DesignTechnical Screen - MercorMediumSoftware EngineerCharge-Then-Save: Making a Checkout Handler Safe Under Retries
Review a ticket-checkout handler that bills a card through a remote gateway and then saves an order row, explain every way it breaks when calls fail or are retried, and redesign it. Tests reasoning about partial failure, idempotency, and reconciliation.
Software Engineering FundamentalsTechnical Screenidempotencydistributed-systemspayments - MercorMediumSoftware EngineerCheck-and-Insert for a Million User IDs: Balancing Latency, Memory and Accuracy
Design a check-and-insert service for about a million user IDs that reports whether an ID already exists and adds it if not. It tests memory estimates, data structure choice, atomic inserts under concurrency, trading memory for accuracy with compact filters, and durable on-disk storage with fast reads and writes.
System DesignTechnical Screen - MercorMediumSoftware EngineerCode Review: A Ride Fare Method That Charges a Card Then Logs the Trip
Review a Java method that charges a rider's card through an external processor and then writes a trip record, and explain what goes wrong if the caller fails mid-call and how to fix it.
Software Engineering FundamentalsTechnical Screencode-reviewidempotencydistributed-systems - MercorEasySoftware EngineerCode Review: Find the Problems in a Python Dict-Based Memoization Cache
A Python code review question about a function that memoizes an expensive computation in a module-level dictionary. It tests whether a candidate can find correctness, memory, concurrency and key-equality problems in simple caching code and propose fixes with clear trade-offs.
Software Engineering FundamentalsTechnical Screen - MercorMediumSoftware EngineerCode Review: Improve a Java Method That Builds a CSV String
A Java code-reading question: review a short method that concatenates a list of rows into a CSV string and propose improvements. It tests knowledge of string-building performance, separator and escaping rules for CSV, null handling, streaming output for large exports, and risks when files are opened in spreadsheets.
Software Engineering FundamentalsTechnical Screen - MercorMediumSoftware EngineerCode Review: Partial Failure in a Java Payment Method That Charges Then Records
A Java code-reading question about a payment method that charges an external provider and then inserts a database record, focused on what happens when the client fails in the middle of the call. It tests reasoning about partial failures, retries, idempotency keys, payment states, and reconciliation with the provider.
Software Engineering FundamentalsTechnical Screen - MercorMediumSoftware EngineerCode Review: Thread Safety of a Python Compute-and-Cache Function
Review a Python function that checks a dictionary cache, runs an expensive computation on a miss, and stores the result, assuming concurrent callers. It probes thread safety under simultaneous misses, making the computation run once per input, where to place a lock without serializing cache hits, and how Python dictionaries behave under concurrent reads and writes.
Software Engineering FundamentalsTechnical Screen - MercorHardSoftware EngineerCompare Merge Sort with Factorial and Randomized Inefficient Sorts
Tests deep understanding of sorting algorithms, contrasting optimal divide-and-conquer strategies (Merge Sort and its adaptive variants) against factorial and randomized paradigms (Permutation Sort and Bogo Sort) across worst-case and expected complexity bounds.
Software Engineering FundamentalsTechnical ScreenDivide and ConquerSortingComplexity Analysis - MercorMediumSoftware EngineerCompare processes and threads in Linux and Python
This question evaluates understanding of operating-system level concurrency versus language-level concurrency, specifically distinctions between processes and threads on Linux, the Global Interpreter Lock in Python, and trade-offs between Python threading and multiprocessing for performance.
Software Engineering FundamentalsTechnical Screen - MercorMediumSoftware EngineerDebug a Java CSV Export Function for Output and Performance Bugs
A debugging exercise on a small Java function that converts rows of string fields into CSV text for import by another system. You find what is wrong with its output and why it slows down sharply on large exports, then fix it. It tests string handling, the cost of building strings in loops, and edge-case tests.
Software Engineering FundamentalsTechnical Screen - MercorEasySoftware EngineerDesign a Deliberately Inefficient Sorting Algorithm and Analyze Its Complexity
An algorithms discussion question that asks for a deliberately inefficient but correct sorting algorithm and a careful analysis of its running time. It tests complexity reasoning about extremely fast-growing costs, worst-case versus expected time, and how such a sort compares with the lower bound for comparison sorting.
Software Engineering FundamentalsTechnical Screen - MercorMediumSoftware EngineerDesign a Project-to-Contractor Matching System
Tests your ability to architect a two-sided matching platform that enforces strict eligibility filters, dynamic availability tracking, multi-stage ranking with exploration, and closed-loop model evaluation.
System DesignTechnical Screensystem-designmatching-enginerecommendation-systems - MercorEasyMachine Learning EngineerDesign a Social Feed
Design an end-to-end personalized social feed system capable of serving low-latency ranked content while handling hybrid fanout, multi-stage ML candidate retrieval, and stable pagination.
System DesignTechnical Screensystem-designfeed-rankingrecommendation-systems - MercorMediumSoftware EngineerDesign an API to Deep-Copy a Dataset with Its Tasks, Model Responses and Grades
A system design question about an API that copies a dataset together with its tasks, model responses and grades so that the copy can be edited independently. It covers ID remapping, background jobs with progress tracking and resumable checkpoints, idempotent requests, worker leases, edits to the source during the copy, and cleanup after failure.
System DesignTechnical Screen - MercorMediumSoftware EngineerDesign the Worst Correct Sorting Algorithm and Analyze Its Complexity
Asks you to propose the worst sorting algorithm that is still correct, explain how it works, argue that it always terminates with sorted output, and analyze its best-case and worst-case time and space. It tests counting arrangements, reasoning about factorial growth and stating what makes such a question well defined.
Software Engineering FundamentalsTechnical Screen - MercorMediumMachine Learning EngineerEvaluate Noisy Data for LLM Post-Training
Design a curation and validation framework to evaluate, filter, and safely integrate a large, noisy dataset into an LLM post-training pipeline without degrading model performance.
Machine LearningTechnical ScreenLLM Post-TrainingData CurationModel Evaluation - MercorMediumSoftware EngineerExplain Kubernetes autoscaling and traffic routing
This question evaluates understanding of Kubernetes autoscaling mechanisms, external-to-pod traffic routing, and the differences between ReplicaSet and StatefulSet controllers.
System DesignTechnical Screen
Lyft
MathWorks
Mercor