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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.
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Showing 841–870 of 1080 results
- RipplingMediumSoftware EngineerImplement Food Delivery Billing
This problem tests your ability to implement complex billing logic involving conditional fee structures, time-based surcharges, and data aggregation.
Coding & AlgorithmsOnsiteAlgorithmsDatetimeData Processing - RipplingMediumSoftware EngineerImplement an In-Memory File System
Design and implement an in-memory file system supporting directory creation, file appending, reading, and lexicographically sorted path listings.
Coding & AlgorithmsOnsitetrietreedesign - RipplingMediumMachine Learning EngineerImplement stack and interval algorithms with tests
This question evaluates implementation-level competencies with fundamental data structures and algorithms—stack-based bracket validation, interval merging with open/closed endpoint semantics, and arithmetic expression evaluation using stacks—while also measuring the ability to design comprehensive unit tests; category: Coding & Algorithms for a Machine Learning Engineer role. It is commonly asked to gauge practical coding ability, correctness under tricky edge cases and input semantics, and test-coverage awareness, representing a practical application-level assessment that also requires conceptual reasoning about invariants and boundary behavior.
Coding & AlgorithmsOnsite - RipplingMediumSoftware EngineerTrack article votes and last three flips
This question evaluates a developer's ability to design in-memory data structures that support constant-time vote updates, score aggregation, and recent flip-event tracking while handling vote-change semantics.
Coding & AlgorithmsOnsite - 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 - 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 - 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 - 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 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 - 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 - 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 EngineerImplement a Log Rate Limiter
This problem tests your ability to design a thread-safe, time-windowed rate limiter using efficient data structures to track event timestamps.
Coding & AlgorithmsOnsiteHash TableDesignConcurrency - RobloxMediumSoftware EngineerImplement a sliding-window rate limiter
Evaluates the candidate's ability to design and implement an in-memory sliding-window rate limiter enforcing per-user and per-game constraints, focusing on correct request-acceptance semantics and efficient timestamp eviction; Category/domain: Coding & Algorithms; Level of abstraction: component-level algorithm and data-structure implementation.
Coding & AlgorithmsOnsite - RobloxMediumSoftware EngineerImplement queue-based rate limiter with multi-key limits
This question evaluates implementation and design skills around rate limiting, including rolling-window counters, multi-key constraints, and atomic updates, and falls under the Coding & Algorithms domain focused on practical application of algorithms and data structures.
Coding & AlgorithmsOnsite - RobloxMediumData ScientistOptimize bread-factory pipeline for max profit
This question evaluates skills in combinatorial optimization, budgeted resource allocation, bottleneck throughput modeling, and algorithm design with cost amortization for maximizing profit under constraints.
Coding & AlgorithmsOnsite - RobloxMediumSoftware EngineerSimulate robot path and detect boundedness
This question evaluates the ability to simulate iterative movement and reason about repeated state transformations, testing competencies in algorithm design, cycle detection, and geometric reasoning; it falls under the Coding & Algorithms category.
Coding & AlgorithmsOnsite - RogoMediumMachine Learning EngineerInfer the Smallest Valid Character Order from Sorted Password Hints
This problem tests your ability to model dependency constraints using a Directed Acyclic Graph (DAG) and apply Kahn's algorithm or DFS-based topological sorting to resolve ordering dependencies.
Coding & AlgorithmsOnsiteGraphTopological SortPriority Queue - RoktEasySoftware EngineerImplement basic calculator with four operations
This question evaluates a candidate's ability to parse and evaluate arithmetic expressions, correctly apply operator precedence and left-to-right associativity, and handle integer arithmetic details such as truncating division, whitespace, and multi-digit numbers, and is commonly asked to assess implementation-level parsing and algorithmic reasoning. The category is Coding & Algorithms and the level of abstraction is practical application, focusing on coding an efficient evaluator that balances time and space constraints rather than purely conceptual theory.
Coding & AlgorithmsOnsite - RokuMediumSoftware EngineerCompute longest common subsequence length
This question tests the ability to solve the Longest Common Subsequence (LCS) problem using dynamic programming to optimize overlapping subproblems.
Coding & AlgorithmsOnsiteDynamic ProgrammingStringsAlgorithms - SIG (Susquehanna)EasySoftware EngineerFind Company Tickers Mentioned in a News Headline
Implement a headline scanner that identifies mentioned company names using whole-word matching and returns their unique stock tickers in the order specified by the input mapping.
Coding & AlgorithmsOnsiteStringsHash TableTrie - SIG (Susquehanna)MediumSoftware EngineerSolve theatre seating and ticker extraction
This question evaluates algorithmic problem-solving skills across two areas: efficient seat-allocation and interval occupancy reasoning for grouping in a constrained seating layout, and robust string processing with phrase-based, case-insensitive matching and mapping to ticker identifiers.
Coding & AlgorithmsOnsite - SalesforceMediumSoftware EngineerBinary Tree Path Sum
Determine if a binary tree contains a root-to-leaf path whose node values add up to a given target sum.
Coding & AlgorithmsOnsiteBinary TreeDFSBFS - SalesforceMediumSoftware EngineerCount the Ways to Split a Digit String into Primes
Tests 1D dynamic programming combined with primality testing to count valid partitions of a digit string into prime segments modulo 10^9 + 7.
Coding & AlgorithmsOnsiteDynamic ProgrammingMathNumber Theory - SalesforceMediumSoftware EngineerDiameter of an Undirected Tree
Tests your ability to traverse an unrooted, undirected tree to compute its diameter (longest simple path) in linear time and space.
Coding & AlgorithmsOnsitetreegraphbfs
Rippling
Robinhood
Roblox
SIG (Susquehanna)
Salesforce