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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
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- 546
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- 11
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- 8
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Showing 391–420 of 1706 results
- CitadelMediumSoftware EngineerDesign a token manager with lazy expiration
This problem tests your ability to design a token management system that supports efficient retrieval, updates, and lazy removal of expired tokens using a combination of a hash map and a priority queue.
Coding & AlgorithmsTechnical ScreenHash MapHeapTTL - CitadelMediumSoftware EngineerFind earliest common meeting slot
This question evaluates proficiency with interval manipulation, timeline merging, and algorithmic reasoning for scheduling constraints, measuring competency in handling sorted interval lists, edge-case sanitization, and complexity analysis.
Coding & AlgorithmsTechnical Screen - CitadelMediumSoftware EngineerFind the Index Range of a Target in a Sorted Array
Implement an algorithm to find the first and last index of a target value in a sorted array in O(log n) time.
Coding & AlgorithmsTechnical Screenbinary-searcharrayscitadel - CitadelMediumSoftware EngineerFind the Shortest Target-Sum Path
This problem tests your ability to navigate binary trees using recursion or iterative traversal while maintaining state to find a path that meets a specific sum criteria with the smallest number of nodes.
Coding & AlgorithmsTechnical ScreenTreesDFSRecursion - CitadelMediumData ScientistImplement Infinite Fibonacci Generator Using Lazy Evaluation
This question evaluates understanding of lazy evaluation and Python generator semantics, testing a candidate's ability to work with iterative sequence production and manage state across iterations.
Coding & AlgorithmsTechnical Screen - CitadelEasySoftware EngineerImplement LRU/LFU cache with custom eviction
This problem tests your ability to design a generic cache structure that supports interchangeable eviction strategies, requiring efficient lookup and metadata management.
Coding & AlgorithmsTechnical ScreenHash MapLinked ListCache - CitadelMediumData ScientistImplement Piecewise Linear Interpolation and Extrapolation
Implement piecewise linear interpolation from unsorted knots, including exact-knot behavior and endpoint extrapolation. Practice paired sorting, binary search, and numerical edge cases.
Coding & AlgorithmsTechnical Screen - CitadelMediumSoftware EngineerImplement a single-producer multi-consumer ring buffer
This question evaluates understanding of ring-buffer data structures, circular indexing, fixed-capacity storage, and object-oriented design for a single-producer, multi-consumer implementation in C++.
Coding & AlgorithmsTechnical Screen - CitadelEasySoftware EngineerImplement an in-memory order book API
This problem tests your ability to design an in-memory data structure for an order book using efficient data structures to support order management and price-level aggregation.
Coding & AlgorithmsTechnical ScreenData StructuresHash MapTree - CitadelMediumData ScientistImplement lazy unique-merge generator for sorted streams
This question evaluates knowledge of lazy evaluation, Python generators/iterators, merging nondecreasing streams with duplicate elimination, and considerations of time and space complexity in streaming contexts.
Coding & AlgorithmsTechnical Screen - CitadelMediumData ScientistImplement two-pointer unique-pair sum search
Implement two-pointer unique-pair sum search 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 & AlgorithmsTechnical Screen - CitadelMediumData ScientistMatch a string with wildcard pattern recursively
This problem tests your ability to implement a recursive pattern-matching algorithm that handles specific wildcard characters while managing overlapping subproblems.
Coding & AlgorithmsTechnical ScreenRecursionDynamic ProgrammingString Matching - CitadelMediumSoftware EngineerMaximize Earnings by Adding Working Days
Maximize schedule earnings by changing at most k days off into working days, balancing fixed daily pay with bonuses for consecutive working days.
Coding & AlgorithmsTechnical Screen - CitadelMediumSoftware EngineerMerge K Drone Telemetry Streams Into a Running Altitude Timeline
Interleave K drones' individually time-ordered altitude logs into a single replay and track the fleet's shared altitude total as each logged change is applied. Tests k-way merging with a heap, a deterministic tie-break across drones, and correct handling of negative deltas and drones with no events.
Coding & AlgorithmsTechnical Screenheapmerge-intervalsstreaming - CitadelMediumSoftware EngineerMerge K Timestamp-Sorted Price Feeds into a Running Absolute Price
Merge K price-event feeds, each already sorted by timestamp, into one chronological stream and return the running absolute price after every event, starting from zero. It tests merging sorted sequences efficiently, a deterministic tie-break for equal timestamps by feed index and then in-feed order, negative deltas, empty feeds, and 64-bit accumulation.
Coding & AlgorithmsTechnical Screen - CitadelMediumSoftware EngineerMerge K timestamped lists with timestamp coalescing
This problem tests your ability to efficiently merge multiple sorted streams of data and aggregate values associated with the same timestamp.
Coding & AlgorithmsTechnical ScreenHeapMerge SortData Streams - CitadelEasySoftware EngineerRead and Write Files with Shared Content
Design an in-memory file system that shares identical content payloads across multiple file paths to save memory, supporting reads, writes, and deduplication tracking.
Coding & AlgorithmsTechnical ScreenHash TableDesignString - CitadelMediumSoftware EngineerReturn a Valid Dependency Order for Named Tasks
Implement a deterministic topological sort for a directed acyclic graph of named tasks with cycle detection and lexicographical tie-breaking.
Coding & AlgorithmsTechnical ScreenGraphTopological SortHeap - CitadelMediumSoftware EngineerReturn nodes on a tree diameter path
This problem tests your ability to perform a two-pass Breadth-First Search (BFS) or Depth-First Search (DFS) on an undirected tree to find the longest path and reconstruct the sequence of nodes that form it.
Coding & AlgorithmsTechnical ScreenTreesGraph TheoryBFS - CitadelMediumSoftware EngineerTop-K Largest Elements in Every Sliding Window
Design an algorithm to maintain and extract the top-K largest elements in descending order for each sliding window of size W across an array.
Coding & AlgorithmsTechnical ScreenSliding WindowHeapOrdered Set - CitadelMediumData ScientistUpdate No-Intercept Regression Slopes Across Batches
Compute cumulative no-intercept regression slopes as paired data arrives in batches. Reuse running cross-products and sums of squares instead of refitting all historical rows.
Coding & AlgorithmsTechnical Screen - CloudKitchensMediumSoftware EngineerAnswer static and streaming Top-K queries
This question evaluates understanding of frequency counting, top-K selection, streaming and sliding-window algorithms and data-structure design in the Coding & Algorithms domain, testing both conceptual algorithmic reasoning and practical implementation skills.
Coding & AlgorithmsTechnical Screen - CloudKitchensMediumSoftware EngineerDesign a menu manager with enums
This question evaluates data modeling with enums, efficient data structure selection to meet specified time complexities, API design for CRUD operations, and practical implementation skills including a command-line interface and unit testing.
Coding & AlgorithmsTechnical Screen - CloudKitchensMediumSoftware EngineerDesign an in-memory cloud storage system
This problem tests your ability to design an efficient in-memory storage manager that handles concurrent file operations, user-based quotas, and data eviction policies.
Coding & AlgorithmsTechnical ScreenData StructuresSystem DesignOptimization - CloudKitchensMediumSoftware EngineerDesign receipt system with combo discounts
A CloudKitchens software-engineer technical screen: build a point-of-sale order that prints an itemized receipt on every item tap, then extend it to apply combo discounts. It tests cart data-structure design, receipt formatting, and the algorithm for selecting a valid set of non-overlapping combos.
Coding & AlgorithmsTechnical Screen - CloudKitchensMediumSoftware EngineerImplement concurrent order-accept/pickup simulator
This question evaluates concurrency and synchronization skills, including thread-safe design, inter-thread communication, state tracking, and correctness properties such as race-condition avoidance and deadlock freedom.
Coding & AlgorithmsTechnical Screen - CloudKitchensMediumSoftware EngineerImplement menu parser and serializer
This question evaluates proficiency in text parsing, hierarchical data modeling, tree construction and serialization, string manipulation, and algorithmic complexity (linear time/space).
Coding & AlgorithmsTechnical Screen - CognitivMediumMachine Learning EngineerMaintain a Streaming Median
This question evaluates understanding of streaming algorithms and dynamic data structures for maintaining order statistics, along with analysis of time complexity and memory trade-offs.
Coding & AlgorithmsTechnical Screen - CoinbaseMediumSoftware EngineerCount users over n connections
This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Count users over n connections states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsTechnical Screen - CoinbaseMediumSoftware EngineerDesign crypto trading order control API
This question evaluates understanding of state management and finite-state machines, API design for lifecycle control, and implementation of in-memory data structures and transition validation in the Coding & Algorithms category.
Coding & AlgorithmsTechnical Screen
Citadel
Coinbase