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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
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- 8
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Showing 5731–5760 of 9403 results
- MolocoadsMediumMachine Learning EngineerCompute the Longest Run of Ones Across Multiple Machines
This problem tests the ability to design a distributed data reduction pattern where partial results can be combined using associative operators to compute a global property.
System DesignOnsiteDistributed SystemsAlgorithmsMapReduce - MolocoadsMediumMachine Learning EngineerFind the Longest Consecutive Run of Ones
Implement an algorithm to find the maximum length of contiguous ones in a binary array without any bit flips, returning 0 for an empty input.
Coding & AlgorithmsOnsitearraystwo-pointerssliding-window - MomentMediumFrontend EngineerBuild a Race-Free Memory Card Game in React
Work through the state and timing logic for a React memory-card game that remains correct under rapid clicks and restarts. The exercise examines stale closures, input locking, timeout cleanup, stable card identity, accessible interaction, and tests for race-prone transitions.
Software Engineering FundamentalsTechnical Screen - MongoDBMediumSoftware EngineerBehavioral: ownership, team play, and a deep dive on a project you led
Senior behavioral interview prompts on ownership, being a strong team player, and leading a project, including hiring manager and director deep dives into past work. It tests specific first-person stories, accountability, collaboration, leadership of people and technical decisions, and consistent detail under repeated probing.
Behavioral & LeadershipOnsite - MongoDBHardSoftware EngineerBuild an Exactly-Once Crawler and Add Safe Concurrency
Build a crawler around a supplied fetch-and-parse API, then add bounded concurrency, atomic discovery, correct completion detection, and explicit failure semantics.
Software Engineering FundamentalsTechnical Screen - MongoDBMediumSoftware EngineerDebug a slow concurrent network server under load
This question tests your ability to diagnose performance bottlenecks in a multi-threaded network server using I/O multiplexing, focusing on how blocking calls and thread management impact latency.
Software Engineering FundamentalsOnsiteConcurrencyPerformance TuningI/O Multiplexing - MongoDBMediumSoftware EngineerDesign a Retail Stock Trading Platform with Live Prices and Reliable Order Handling
A senior system design question asking you to build a retail stock trading platform where users stream live prices, place and cancel market and limit orders, and track positions and cash. It tests order state machines, idempotent submission, buying-power holds, venue integration and real-time price fan-out to many clients.
System DesignOnsite - MongoDBMediumSoftware EngineerDesign a small-scale metrics monitoring system for database instances in the cloud
System design question: design a small-scale monitoring system for database instances running on public clouds, covering which metrics to collect, ingestion and query APIs, tracking how metrics change over time, and scaling to near real-time with Kafka and Flink. Alerting and notifications are out of scope.
System DesignOnsite - MongoDBMediumSoftware EngineerDesign iterator for sorted union
This problem tests your ability to design an iterator that merges multiple sorted streams of integers while performing on-the-fly deduplication using minimal extra memory.
Coding & AlgorithmsTechnical ScreenHeapIteratorsMerge Sort - MongoDBMediumSoftware EngineerEvaluate a Nested Predicate Expression Tree
Implement an evaluator for a serialized predicate expression tree against JSON documents, testing recursion, AST handling, and field resolution.
Software Engineering FundamentalsTechnical Screenrecursiontreesdesign - MongoDBMediumSoftware EngineerExplain Modern Python Features and Ecosystem
This question assesses your depth of knowledge regarding modern Python language evolution, the utility of popular libraries, and internal implementation details that impact memory and performance.
Software Engineering FundamentalsHR ScreenPythonInternalsMemory Management - MongoDBMediumSoftware EngineerHow do you answer common HR screen questions?
This question set evaluates senior-level behavioral competencies including professional storytelling, interpersonal communication, alignment with technical and cultural fit, and readiness to discuss compensation and career trajectory.
Behavioral & LeadershipHR Screen - MongoDBHardSoftware EngineerImplement a Finite Concurrent Web Crawler
Implement an orchestrator for a finite concurrent web crawler featuring transactional URL state tracking, per-host politeness rate-limiting, classified error handling, and robust termination detection.
Software Engineering FundamentalsOnsiteConcurrencySystem DesignQueues - MongoDBMediumSoftware EngineerImplement a Lazy Union Iterator Over Two Strictly Sorted Iterators
Implement a UnionIterator that lazily merges two strictly sorted iterators of integers or strings into one strictly sorted iterator without duplicates, using constant extra memory. Tests iterator protocol design, one-element lookahead, cross-input deduplication, end-of-stream behavior and edge cases such as empty inputs.
Software Engineering FundamentalsTechnical Screen - MongoDBMediumSoftware EngineerImplement a sliding-window rate limiter (n requests per k seconds), then make it per key
Coding and design question from a technical screen: implement a rate limiter that admits at most n requests in any k-second sliding window, then make it thread-safe and key-specific. It tests window boundary semantics, amortized complexity, race conditions and locking, per-key state creation and memory bounds.
Software Engineering FundamentalsTechnical Screen - MongoDBMediumSoftware EngineerImplement a thread-safe high-concurrency LRU cache
This problem tests your ability to design a thread-safe LRU cache using a combination of a hash map and a doubly linked list, requiring efficient synchronization to handle concurrent access.
Coding & AlgorithmsOnsiteConcurrencyLRU CacheHash Map - MongoDBMediumSoftware EngineerReason About Recursive Key Search in Nested JSON
Implement a recursive search function to extract all values associated with a given key from deeply nested JSON documents containing arbitrary combinations of dictionaries and lists.
Software Engineering FundamentalsTechnical ScreenRecursionJSONTree Traversal - MongoDBMediumSoftware EngineerSummarize background, challenge project, and failure
This prompt evaluates leadership, technical ownership, communication, system-design reasoning, and incident-analysis competencies by requesting a concise career narrative, a deep-dive into a challenging project (including constraints, trade-offs, architecture, validation, and metrics), and a meaningful failure retrospective.
Behavioral & LeadershipTechnical Screen - MongoDBMediumSoftware EngineerSuppress repeat log messages printed within 10 seconds of their last printed occurrence
Coding practice question: process a time-ordered stream of log messages and decide which ones are printed when the same text may print at most once every 10 seconds. It tests tracking state across a stream, exact boundary handling at the 10-second mark, and correctly ignoring suppressed events.
Coding & AlgorithmsOther - Moody'sMediumSoftware EngineerDesign a Product Inventory and Pricing Service
Design a high-throughput product catalog, dynamic pricing, and inventory management service that delivers low-latency browsing while guaranteeing transactional correctness and preventing overselling at checkout.
System DesignOnsitesystem-designdistributed-systemscaching - Moody'sMediumSoftware EngineerReturn Binary Search Tree Values in Ascending Order
This problem tests the ability to deserialize a level-order encoded Binary Search Tree into a tree structure and perform an in-order traversal to retrieve sorted values.
Coding & AlgorithmsOnsiteBinary TreeBSTDeserialization - Morgan StanleyMediumData ScientistAnswer basic probability and statistics questions
This problem tests your conceptual understanding of probability distributions, statistical bias in data collection, and the relationship between covariance and linear correlation.
Machine LearningOnline AssessmentStatisticsProbabilityBias - Morgan StanleyMediumSoftware EngineerCompute minimal cost to merge numbers
Compute minimal cost to merge numbers evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsOnline Assessment - Morgan StanleyEasyData ScientistCompute win probability in coin-toss game
This question evaluates understanding of probability theory and stochastic processes, focusing on win probability in an alternating coin-toss game and reasoning about pattern occurrence and stopping times in random sequences.
Coding & AlgorithmsTechnical Screen - Morgan StanleyMediumSoftware EngineerCount decodings of a digit string
Count decodings of a digit string evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsOnline Assessment - Morgan StanleyMediumData ScientistDescribe Your Analysis and Visualization Toolkit
Tests your ability to articulate an end-to-end data analysis and visualization workflow clearly and concisely for recruiters and hiring managers, connecting technical tool choices directly to business outcomes.
Data Manipulation (SQL/Python)HR Screendata-analysissqlpython - Morgan StanleyMediumData ScientistEstimate Greeks and hedging PnL
This question evaluates understanding of option Greeks (delta, gamma, vega), mental approximation of Gaussian probabilities, and the ability to reason about delta-hedged profit-and-loss under Black-Scholes model misspecification, categorized under Software Engineering Fundamentals for a Data Scientist role.
Software Engineering FundamentalsTechnical Screen - Morgan StanleyMediumData ScientistExplain Your Risk Analytics Work to a Recruiter
This question tests your ability to translate complex technical risk modeling into a compelling professional narrative that emphasizes business impact, stakeholder collaboration, and personal accountability.
Behavioral & LeadershipHR ScreenBehavioralRisk AnalyticsStakeholder Management - Morgan StanleyEasyData ScientistExplain forward contracts and options
This question evaluates understanding of financial derivatives—specifically forwards and options—assessing competency in financial instruments, contractual rights and obligations, pricing concepts, and how these concepts inform data-driven modeling for a Data Scientist role.
Software Engineering FundamentalsTechnical Screen - Morgan StanleyMediumData ScientistImplement Factorial and Squares
A Morgan Stanley data scientist HR-screen live-coding warm-up: implement Python `factorial(n)` (iteratively, then explain the recursive version) and `squares(n)` returning the squares of the first n integers. Evaluates clean Python, the iteration-vs-recursion trade-off, time and space complexity analysis, input validation, and edge cases like n = 0 and negative input.
Coding & AlgorithmsHR Screen
MongoDB
Morgan Stanley