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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 721–750 of 1080 results
- NooksMediumSoftware EngineerImplement a BFS web crawler
This question evaluates proficiency in breadth-first search and graph traversal concepts applied to web crawling, including handling duplicate links, hostname filtering, and tracking visited URLs.
Coding & AlgorithmsOnsite - NotionMediumSoftware EngineerFind Top Errors in Time Window
This problem tests your ability to process streaming log data within a sliding time window, aggregate frequencies using hash maps, and implement custom sorting logic.
Coding & AlgorithmsOnsiteHash MapSortingData Processing - NuroHardBackend EngineerImplement BFS and a Job Scheduler
Solve grid reveal with BFS and design a thread-safe periodic job scheduler. The solution covers Minesweeper-style expansion, queue processing, priority-queue scheduling, locks, worker pools, cancellation, duplicate prevention, long-running tasks, clock drift, and backpressure.
Coding & AlgorithmsOnsite - OmnissaMediumSoftware EngineerAlternate Odd and Even Numbers with Two Threads
This problem tests knowledge of thread synchronization using locks and condition variables to enforce a specific execution order between two concurrent processes.
Coding & AlgorithmsOnsiteConcurrencyMultithreadingSynchronization - OmnissaMediumSoftware EngineerCheck Whether a Singly Linked List Is a Palindrome
Tests the ability to determine if a singly linked list is a palindrome in O(n) time and O(1) auxiliary space using two pointers and in-place list reversal.
Coding & AlgorithmsOnsiteLinked ListTwo PointersIn-Place Reversal - OmnissaMediumSoftware EngineerFind the Celebrity from a Knows Matrix
This problem tests the ability to solve a search problem in O(N) time by utilizing the transitive and exclusionary properties of the 'knows' relationship to eliminate candidates.
Coding & AlgorithmsOnsiteArraysTwo PointersAlgorithms - OmnissaMediumSoftware EngineerFind the Maximum Sum of a Contiguous Subarray
This problem tests the ability to implement Kadane's algorithm to find the maximum sum of a contiguous subarray, specifically focusing on handling negative integers and maintaining optimal time and space complexity.
Coding & AlgorithmsOnsiteArraysDynamic ProgrammingKadane's Algorithm - OmnissaMediumSoftware EngineerRepeatedly Remove Adjacent Equal Characters
This problem tests your ability to handle recursive reduction patterns in a string using a stack-based approach to achieve linear time complexity.
Coding & AlgorithmsOnsiteStackStringGreedy - OpenAIMediumSoftware EngineerAdd Consecutive-Value Bonuses to Grid Paths
Tests dynamic programming on a 2D grid with extended state tracking to incorporate multi-step path history for score bonuses, path counting, and lexicographical path reconstruction.
Coding & AlgorithmsOnsitedynamic-programminggridpathfinding - OpenAIHardSoftware EngineerAggregate Recent Message Events And Active Chats
Design an in-memory aggregation system that tracks rolling window message counts and distinct active entities across chats with bounded memory and O(1) amortized operations.
Coding & AlgorithmsOnsiteSliding WindowData StreamsDesign - OpenAIMediumSoftware EngineerCompute infection spread time
This problem tests your ability to model a spreading process on a 2D grid using a multi-source Breadth-First Search (BFS) to determine the time required for a state to propagate across the entire space.
Coding & AlgorithmsOnsiteBFSGraphsGrid - OpenAIMediumSoftware EngineerDesign a parser for a hypothetical language
This question evaluates competency in compiler and language design, covering grammar analysis, parsing algorithms (LL/LR/GLR/Earley/PEG), lexer and parser implementation, AST construction, error reporting and recovery, operator precedence and associativity, and analysis of time/space trade-offs.
Coding & AlgorithmsOnsite - OpenAIMediumMachine Learning EngineerFind Minimum Compatible Version
Implement an algorithm to find the earliest compatible software version while minimizing expensive compatibility-check API calls across partitioned version branches.
Coding & AlgorithmsOnsiteBinary SearchAlgorithmsOptimization - OpenAIMediumMachine Learning EngineerFind the First Working Version
This question tests the ability to combine custom comparison logic with a binary search approach to identify the first transition point in a monotonic sequence.
Coding & AlgorithmsOnsiteBinary SearchAlgorithmsOptimization - OpenAIHardSoftware EngineerImplement Disease and Friend Snapshot Models
This question evaluates skills in graph-based modeling and temporal state simulation as well as the design and implementation of snapshot-capable directed graph data structures, covering competencies in propagation and state transitions (including immunity, recovery, and death), efficient snapshotting, querying, ranking, and diffing of follow relationships. It is commonly asked to assess algorithmic reasoning, correctness under edge cases, and complexity-aware implementation; the problem belongs to the Coding & Algorithms domain and tests both conceptual understanding of dynamic graph behavior and practical application-level implementation of data structures and immutable snapshots.
Coding & AlgorithmsOnsite - OpenAIHardSoftware EngineerImplement IP Address Arithmetic
Implement parsing, binary representation, arithmetic offsets, and canonical formatting for both IPv4 and IPv6 addresses and CIDR subnets.
Coding & AlgorithmsOnsitebit-manipulationstring-parsingnetworking - OpenAIMediumSoftware EngineerImplement an IPv4 Iterator
This problem tests your ability to handle IPv4 address arithmetic, bitwise operations, and the implementation of a stateful iterator that supports bidirectional traversal and range generation from CIDR notation.
Coding & AlgorithmsOnsiteBit ManipulationIterator PatternNetworking - OpenAIHardSoftware EngineerImplement an in-memory SQL-like table
This question evaluates implementation skills for an in-memory SQL-like table, focusing on data modeling with nested key-value structures, string handling, efficient lookups, and lexicographic sorting with tie-breaking.
Coding & AlgorithmsOnsite - OpenAIHardMachine Learning EngineerImplement in-memory database insert and delete operations
This question evaluates understanding of data structures and algorithmic complexity in the context of designing a key-value in-memory database, and it falls under the Coding & Algorithms domain for a Machine Learning Engineer role while focusing on practical implementation skills.
Coding & AlgorithmsOnsite - OpenAIMediumMachine Learning EngineerInfer Generic Return Types
Implement a toy type-inference engine that unifies generic parameter types with concrete argument types and substitutes resolved type variables to determine the return type.
Coding & AlgorithmsOnsiterecursiontreetype-systems - OpenAIHardSoftware EngineerLeftmost-Fit Memory Allocator: Allocate Consecutive Units and Free by Owner
Simulate a memory allocator over n units: each allocation takes the leftmost run of consecutive free units for an owner, and each free releases all of that owner's units. Return the result of every operation. It tests interval bookkeeping and logarithmic-time search for free runs at up to 100,000 operations.
Coding & AlgorithmsOnsite - OpenAIHardSoftware EngineerLeftmost-Fit Theater Row Booking With Bulk Cancellation by Group
Simulate booking a single theater row of n seats, where each booking takes the leftmost block of consecutive free seats for a group and a cancellation releases every seat that group currently holds anywhere in the row. Tests augmented-interval bookkeeping and logarithmic-time search for the best free run.
Coding & AlgorithmsOnsitesegment-treeintervalssimulation - OpenAIMediumSoftware EngineerReturn the Lexicographically Smallest Topological Order
Implement a deterministic topological sort using a min-heap to return the lexicographically smallest ordering of a directed graph, or detect cycles and return an empty list.
Coding & AlgorithmsOnsitegraphtopological-sortheap - OpenAIHardMachine Learning EngineerSchedule Incremental Labeling Tasks
This problem tests the ability to design an incremental task scheduler that balances workload across a pool of annotators while maintaining fairness and deterministic state transitions.
Coding & AlgorithmsOnsiteHeapsSchedulingGreedy - OpenAIHardMachine Learning EngineerSearch Monster Battle Strategies
Design a search algorithm using state-space exploration to find the minimum number of turns required to defeat a boss given transient health, scripted boss attacks, and a single-use revive.
Coding & AlgorithmsOnsiteBreadth-First SearchState Space SearchGraph Algorithms - OpenAIHardMachine Learning EngineerSimulate Plant Infection With Controlled Burning
This question evaluates a candidate's ability to implement discrete-time grid simulations with delayed state transitions, reason about simultaneous updates and neighborhood effects, and perform a limited combinatorial optimization (choosing one row or column) to minimize a global outcome.
Coding & AlgorithmsOnsite - OpenAIMediumMachine Learning EngineerSimulate Turn-Based Monster Battles
This problem tests your ability to design a stateful simulation engine that handles turn-based mechanics, complex status modifiers, and dynamic combat interactions.
Coding & AlgorithmsOnsiteSimulationState ManagementGame Logic - OpenAIMediumMachine Learning EngineerTrack Expiring GPU Credits
Design an in-memory credit ledger to track expiring GPU compute credits, support priority consumption, and manage resource debt.
Coding & AlgorithmsOnsiteHeapDesignGreedy - OracleMediumBackend EngineerAdd One to an Integer Stored as Digits Without ArrayList
This problem tests array manipulation skills and the ability to handle carry-over logic in fixed-size numerical representations.
Coding & AlgorithmsOnsiteArraysMathAlgorithms - OracleMediumSoftware EngineerCount Islands and Return the Largest Island Size
Count four-connected islands and find the largest island using DFS or BFS, with correct visited-state handling and all-water behavior.
Coding & AlgorithmsOnsite
Notion
Nuro
OpenAI
Oracle