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Coding & Algorithms 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 2461–2490 of 3276 results
- RobinhoodHardData EngineerAggregate user logs into 30-minute sessions
This question evaluates data engineering competencies in time-series sessionization, datetime parsing and arithmetic, grouping and aggregation, distinct-count computation, and CSV log processing.
Coding & AlgorithmsTechnical Screen - RobinhoodMediumFrontend EngineerBuild a Weekly Calendar
This question evaluates frontend UI engineering skills, focusing on interactive interface construction, event handling, and state modeling to maintain a single source of truth for events in a weekly calendar grid, and it belongs to the web frontend development and UI/state-management domain.
Coding & AlgorithmsOnsite - RobinhoodMediumSoftware EngineerCompute Load Factors in a Service Dependency DAG
Calculate downstream request multipliers for services in a directed acyclic graph (DAG) starting from an entrypoint service, accounting for converging dependency paths and unreachable nodes.
Coding & AlgorithmsTechnical ScreenGraphTopological SortDAG - RobinhoodMediumSoftware EngineerCompute dependency load factors in a DAG
This problem tests your ability to model dependencies in a Directed Acyclic Graph (DAG) and calculate the cumulative 'load' contribution of each node, requiring efficient graph traversal techniques like topological sorting or recursion with memoization.
Coding & AlgorithmsTechnical ScreenGraphDAGRecursion - RobinhoodMediumSoftware EngineerCompute nearest gate distance in grid
This problem tests your ability to perform multi-source Breadth-First Search (BFS) on a grid to find the shortest distance from every cell to the nearest target (gate).
Coding & AlgorithmsTechnical ScreenBFSGraphsGrid - RobinhoodEasySoftware EngineerCompute trigger counts in a DAG
This question evaluates understanding of directed acyclic graphs, graph traversal and accumulation of values across dependency edges, as well as algorithmic efficiency for handling large sparse graphs.
Coding & AlgorithmsTechnical Screen - RobinhoodHardSoftware EngineerCount Unique Dependents in a Referral DAG
Count unique direct and transitive dependents in a DAG, preserving edge direction, ignoring unknown endpoints, and handling shared descendants without double-counting.
Coding & AlgorithmsOnsite - RobinhoodMediumBackend EngineerCount and Rank Words in a Paragraph
This problem tests string manipulation, hash map usage for frequency counting, and custom sorting logic for deterministic ordering.
Coding & AlgorithmsTechnical ScreenStringsHash MapSorting - RobinhoodMediumSoftware EngineerDesign a constrained cache and secure string validator
This question tests the ability to implement a thread-safe, size-constrained cache (LRU-like) and robust string validation logic for identifying malformed or potentially malicious input strings.
Coding & AlgorithmsOnsiteConcurrencyLRUHashing - RobinhoodMediumSoftware EngineerDesign a referral leaderboard with chain-based counts
This question evaluates a candidate's ability to model and compute transitive referral counts using graph-like structures and efficient data structures, testing skills in algorithm design, counting, and sorting within the Coding & Algorithms domain.
Coding & AlgorithmsOnsite - RobinhoodEasySoftware EngineerDesign in-memory payment and friendship system
This question evaluates object-oriented design skills, stateful in-memory data structures, request processing, and correctness constraints such as friend relationships, unique request IDs, and atomic balance transfers.
Coding & AlgorithmsTechnical Screen - RobinhoodMediumSoftware EngineerFlatten Fractional-Share Inventory and Record Trade Logs
Process fractional-share buys and sells with exact hundredth units, whole-share market flattening, dollar-order conversion, and ordered inventory-perspective logs.
Coding & AlgorithmsTechnical Screen - RobinhoodMediumData ScientistIdentify Overlapping Sessions and Optimize Coverage
This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Identify Overlapping Sessions and Optimize Coverage states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsTechnical Screen - RobinhoodMediumSoftware EngineerImplement string-based candlestick classifier
This question evaluates string parsing, streaming input processing, numeric validation, and attention to time/space complexity in the Coding & Algorithms category, focusing on efficient single-pass parsing and O(1) extra space constraints.
Coding & AlgorithmsTechnical Screen - RobinhoodMediumSoftware EngineerMaintain Fractional Stock Inventory Across Orders
Simulate sequential customer fractional buy and sell orders, using scaled integer arithmetic to maintain the firm's remaining inventory between 0 and 1 share while tracking whole-share market executions.
Coding & AlgorithmsOnsitesimulationmathhash-table - RobinhoodMediumSoftware EngineerParse Requests and Compute Balances
This problem tests your ability to parse structured text commands, manage relational state between users, and implement transactional logic with integrity constraints.
Coding & AlgorithmsOnsiteHash MapGraphParsing - RobinhoodMediumSoftware EngineerProduce a Deterministic Course Plan
Return the lexicographically smallest valid course order from prerequisite pairs, or report a cycle. Handle duplicate edges, malformed IDs, self-dependencies, empty course sets, and large graphs with deterministic topological sorting.
Coding & AlgorithmsOnsite - 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 - RobloxMediumSoftware EngineerDesign robot path boundedness with repeats
This question evaluates algorithmic skills in parsing compressed instruction strings, finite-state simulation, and spatial reasoning to determine path boundedness, and it belongs to the Coding & Algorithms domain.
Coding & AlgorithmsOnsite - RobloxMediumSoftware EngineerDetect robot state after movements
This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Detect robot state after movements states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsOnsite - RobloxMediumSoftware EngineerDetect runs and collapse a numeric grid
This question evaluates proficiency in 2D array manipulation, pattern detection for contiguous runs, and state simulation involving removal and gravity-like collapse of elements.
Coding & AlgorithmsOnsite - 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 - RobloxMediumMachine Learning EngineerFind Windows Containing a Target
This problem tests your ability to efficiently filter and identify intervals within a collection that satisfy specific containment constraints using two-pointer or sliding window techniques.
Coding & AlgorithmsOnsiteArraysFilteringIntervals - 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 - RobloxMediumMachine Learning EngineerFind target-heavy sliding windows
This question tests the ability to implement an efficient sliding window algorithm to analyze frequency-based patterns within a data stream or array.
Coding & AlgorithmsOnsiteSliding WindowAlgorithmsArray - RobloxMediumSoftware EngineerFind the Longest Safe Straight-Line Movement on a Laser Grid
Find a robot's longest safe straight-line movement on a laser-covered grid, where only the initial cell is protected and laser rows and columns are blocked.
Coding & AlgorithmsOnline Assessment - 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
Robinhood
Roblox