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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 2251–2280 of 3276 results
- ParadromicsMediumSoftware EngineerImplement a hash table with put/get
This question evaluates implementation and design skills for hash-based data structures, testing competency in data structures, hashing, collision handling, and achieving expected O(1) put/get performance in the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - PatreonMediumSoftware EngineerAnalyze Reports in a Nested Org Chart
This problem tests your ability to model hierarchical tree structures and use post-order traversal to aggregate data across deep organizational levels efficiently.
Coding & AlgorithmsTechnical ScreenTreesGraphsRecursion - PatreonEasySoftware EngineerDesign org chart lookup with preprocessing
This question evaluates skills in data structures and algorithms, specifically tree/forest representation, aggregation of subtree metrics, dynamic updates, and rigorous time and space complexity analysis.
Coding & AlgorithmsTechnical Screen - PayPalMediumSoftware EngineerAssess HashMap vs ConcurrentHashMap
This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Assess HashMap vs ConcurrentHashMap states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsTechnical Screen - PayPalMediumSoftware EngineerCompare final, finally, finalize
This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Compare final, finally, finalize states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsTechnical Screen - PayPalMediumSoftware EngineerCompare write-back vs write-through caches
This question evaluates understanding of caching policies and memory/storage hierarchy trade-offs, focusing on how write-back and write-through handle writes, coherence, durability, latency, bandwidth, dirty bits, write amplification, and power-loss risks.
Coding & AlgorithmsTechnical Screen - PayPalHardData ScientistCompute Variance from a Python List
This question evaluates understanding of basic statistical concepts and numerical computation—specifically population versus sample variance—and tests algorithmic implementation skills, edge-case handling, and complexity reasoning within the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - PayPalEasyData ScientistCompute variance of a list in Python
This question evaluates understanding of statistical measures and numeric computation, focusing on implementing variance calculations (population vs sample) and considerations for numerical stability.
Coding & AlgorithmsTechnical Screen - PayPalMediumSoftware EngineerContrast TCP vs UDP; detect loss
This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Contrast TCP vs UDP; detect loss states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsTechnical Screen - PayPalMediumData ScientistCount Word Frequency and Print Top Three Words
This question evaluates proficiency in basic Python programming, string/text processing, frequency counting and sorting algorithms, reflecting core competencies for data manipulation tasks.
Coding & AlgorithmsOnsite - PayPalMediumSoftware EngineerExplain HashMap internals and collisions
This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Explain HashMap internals and collisions states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsTechnical Screen - PayPalMediumSoftware EngineerExplain Java volatile semantics
This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Explain Java volatile semantics states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsTechnical Screen - PayPalHardData ScientistExplain differences between Python list and tuple
Evaluates understanding of Python data structures—specifically lists versus tuples—by probing concepts such as mutability and its implications, high-level performance and memory trade-offs, typical use cases, and hashability for use as dictionary keys.
Coding & AlgorithmsTechnical Screen - PayPalMediumSoftware EngineerFind k most frequent in linear time
This question evaluates a candidate's ability to design and analyze efficient frequency-counting algorithms and related data structures, testing competencies in hashing, bucket-based grouping, heap usage, and time/space complexity reasoning.
Coding & AlgorithmsTechnical Screen - PayPalMediumData ScientistImplement sliding-window device anomaly
This question evaluates understanding of streaming algorithms, sliding-window state management, per-user data structures, and handling out-of-order events under strict time and space complexity constraints.
Coding & AlgorithmsTechnical Screen - PayPalMediumMachine Learning EngineerMaximize ones with limited flips
This question evaluates proficiency with array algorithms, particularly sliding-window and two-pointer reasoning, complexity analysis, and the ability to adapt solutions for streaming data.
Coding & AlgorithmsOnsite - PayPalMediumSoftware EngineerMinimize a String Using Allowed Swaps
This question evaluates understanding of graph connectivity and constrained string reordering, along with proficiency in applying efficient data structures and algorithms for handling large inputs.
Coding & AlgorithmsOnsite - PayPalMediumMachine Learning EngineerSearch a word in a grid
This question evaluates proficiency in grid traversal and stateful search techniques such as depth-first search and backtracking, including visited-state management and pruning strategies within the Coding & Algorithms domain.
Coding & AlgorithmsOnsite - PayPalMediumSoftware EngineerSolve common search/parse/graph frequency tasks
This problem tests your ability to perform a binary search on a rotated sorted array and subsequently count occurrences of elements to identify the top-k most frequent items.
Coding & AlgorithmsTechnical ScreenBinary SearchHash TableHeap - PeregrineMediumSoftware EngineerFetch, group, and print paginated activities
This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Fetch, group, and print paginated activities states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsTechnical Screen - PermitflowMediumSoftware EngineerDistinguish Permit Requirement Outcomes
This problem tests your ability to model state transitions based on complex rule sets and implement efficient logic to resolve status precedence when multiple criteria are met.
Coding & AlgorithmsTechnical ScreenAlgorithmsLogicSet Theory - PerplexityMediumSoftware EngineerDesign a CreditTracker with expirations
This question evaluates a candidate's ability to design and implement data structures and algorithms for managing time-bound resources with non-monotonic (out-of-order) operations, emphasizing correctness and efficiency within the coding & algorithms domain.
Coding & AlgorithmsTechnical Screen - PerplexityMediumSoftware EngineerImplement Dependency-Aware To-Do List
Design an in-memory task management system that tracks directed dependencies between tasks, prevents cycles, and unblocks dependent tasks upon completion.
Coding & AlgorithmsTechnical ScreenGraphDesignTopological Sort - PerplexityMediumData ScientistImplement Stratified Sampling by Country
Implement proportional stratified sampling on an in-memory list of records partitioned by a categorical key, ensuring exact sample size via the largest remainder method and reproducible selection.
Coding & AlgorithmsTechnical Screenalgorithmsstatisticssampling - PerplexityHardSoftware EngineerImplement Task Dependencies and Failure
This question evaluates understanding of graph-based data structures and algorithms for modeling bidirectional task dependencies, status tracking, and efficient cascading failure propagation in an in-memory task manager.
Coding & AlgorithmsTechnical Screen - PerplexityMediumSoftware EngineerImplement time-versioned KV store with restore
This question evaluates a candidate's ability to design and implement a time-versioned key–value store, assessing knowledge of temporal data structures, versioning semantics, time-travel and range queries, deletion semantics, and rollback/restoration.
Coding & AlgorithmsOnline Assessment - PersonaHardSoftware EngineerImplement a Versioned Key-Value File Store
Practice a Persona coding interview problem focused on implement a versioned key-value file store. The prompt emphasizes edge cases, clean implementation, and verifiable test behavior without revealing the solution.
Coding & AlgorithmsOnline Assessment - PikaHardSoftware EngineerEvaluate Spreadsheet Cells and Reject Circular References
Implement a small spreadsheet whose cells hold integers or single-reference formulas with offsets. Evaluate through current dependencies, propagate updates, report unset chains, and reject a formula atomically whenever it would introduce a circular reference.
Coding & AlgorithmsTechnical Screen - PikaMediumSoftware EngineerImplement text formatter and sum subarray products
This question evaluates algorithmic problem-solving and implementation skills across string formatting (line breaking and space management) and array-based combinatorial computation (sum of subarray products), emphasizing correctness, edge-case handling, and analysis of time and space complexity.
Coding & AlgorithmsOnline Assessment - PilotEasySoftware EngineerSolve Anagram Without Sorting
This question evaluates proficiency in string manipulation, character frequency analysis, and asymptotic time/space complexity reasoning. It is commonly asked in the coding & algorithms domain to test practical application of basic data structures (string processing and frequency-based counting), correctness under input constraints, and the ability to design efficient, linear-time solutions rather than purely conceptual reasoning.
Coding & AlgorithmsTechnical Screen
PayPal
Perplexity