Topic
Coding & Algorithms interview questions
3276 Coding & Algorithms questions from 366 companies, with hints, runnable code and solution walkthroughs.
273 easy2539 medium464 hard
Coding & Algorithms interview questions by the numbers
Last updated
Katkat has 3,276 Coding & Algorithms interview questions from 366 companies; the most come from Amazon (7%), Meta (7%) and Google (6%). By difficulty: 8% easy, 78% medium and 14% hard. The most common round is Technical Screen (52%). Frequent concepts include Algorithms, Data Structures, Arrays and Greedy.
Companies (366)
Difficulty
- Easy8% · 273
- Medium78% · 2539
- Hard14% · 464
Interview rounds
- Technical Screen52% · 1706
- Onsite33% · 1080
- Online Assessment13% · 427
- HR Screen1% · 37
- Other1% · 26
Roles
- Software Engineer80% · 2629
- Machine Learning Engineer8% · 253
- Data Scientist7% · 241
- Data Engineer1% · 45
- Backend Engineer1% · 26
Frequent concepts
- Algorithms9% · 302
- Data Structures7% · 228
- Arrays5% · 176
- Greedy5% · 164
- Optimization5% · 151
- Hash Map4% · 124
Most mentioned in interview experiences
- 1.Solve Algorithmic Challenges in Online Coding Assessments15 reports
- 2.Solve LeetCode string and list problems11 reports
- 3.Solve sliding-window and heap problems8 reports
- 4.Implement LRU cache with O(1) ops7 reports
- 5.Implement and Analyze an LRU Query Cache6 reports
- 6.Determine Length of Longest Unique Substring5 reports
- 7.Match-3 Grid: Find Horizontal and Vertical Runs, Then Clear and Drop Cells5 reports
- 8.Design a single- and multi-threaded web crawler4 reports
- 9.Find an Exit in a URL Maze4 reports
- 10.Find deployable slots in a recurring week from allowed and freeze windows4 reports
Counted from 781 candidate interview experiences on Katkat. How we collect and count
Showing 2401–2430 of 3276 results
Implement a per-IP sliding-window rate limiter: given request timestamps, IP addresses, a request limit and a window length, decide in order whether each request is accepted or rejected. Tests exact window-boundary semantics, per-IP state, and processing a request log efficiently.
RampSoftware EngineerCoding & AlgorithmsOnline AssessmentBuild a fixed-grid string spreadsheet with concatenation formulas, dependency updates, repeated references, and read-time circular-reference errors.
RampSoftware EngineerCoding & AlgorithmsOnsiteThis question evaluates competency in processing and aggregating temporal event data, including time-interval reasoning, counting/grouping per user, and designing efficient data structures and algorithms for large datasets.
RampSoftware EngineerCoding & AlgorithmsTechnical ScreenThis problem tests BFS traversal skills combined with state management for handling intermittent network failures and API constraints.
RampSoftware EngineerCoding & AlgorithmsOnsiteThis problem tests proficiency with hash map operations and handling data retrieval edge cases within an in-memory data store.
RbcroyalbankMachine Learning EngineerCoding & AlgorithmsTechnical ScreenCompare two tokenized sentences using undirected, transitive synonym relationships. Sentence lengths and word positions must match, while a union-find or graph traversal groups chained synonyms and leaves unknown words equivalent only to themselves.
Read.AiSoftware EngineerCoding & AlgorithmsTechnical ScreenGiven discussion comments that form reply trees, each flagged as being about cats, dogs, both or neither, return every comment a cat person or a dog person should not see, where hiding a comment also hides all of its replies. Tests reasoning over tree structure, edge cases such as missing parents, and complexity analysis.
RedditMachine Learning EngineerCoding & AlgorithmsOnsiteSearch a letter grid for a word along one fixed direction, with explicit diagonal rules, boundaries, and rejection of paths that turn.
RedditSoftware EngineerCoding & AlgorithmsTechnical ScreenThis question evaluates graph traversal and shortest-path search skills, specifically reasoning about BFS vs DFS, string transformation modeling, and algorithmic time/space complexity within the Coding & Algorithms domain.
RedditSoftware EngineerCoding & AlgorithmsTechnical ScreenThis problem tests your ability to design a thread-safe, in-memory key-value store and implement basic command parsing for an asynchronous network service.
RedditMachine Learning EngineerCoding & AlgorithmsTechnical ScreenThis problem tests your ability to design a rate-limiting algorithm that calculates traffic volume within a sliding time window to prevent API abuse.
RedditSoftware EngineerCoding & AlgorithmsOnsiteThis problem tests your ability to merge overlapping intervals efficiently using sorting and greedy techniques, a foundational skill for data reconciliation tasks.
RedditSoftware EngineerCoding & AlgorithmsOnsiteDesign and implement an in-memory moderator management system supporting community-specific hierarchies, seniority-based permissions, and rank mutations.
RedditSoftware EngineerCoding & AlgorithmsTechnical ScreenThis problem tests your ability to manipulate string prefixes to satisfy palindromic properties and your skill in performing in-place linked list reordering based on node index parity.
RedditMachine Learning EngineerCoding & AlgorithmsOnsiteThis question evaluates skills in efficient membership testing for large datasets, memory-time trade-offs in data structures, and string handling concerns such as case sensitivity and Unicode normalization.
ReevoSoftware EngineerCoding & AlgorithmsOnline AssessmentThis question evaluates proficiency with string algorithms and algorithmic problem-solving, focusing on palindrome detection and counting contiguous substrings. It is commonly asked to assess implementation skills and the ability to reason about time and space complexity within the Coding & Algorithms domain, emphasizing practical application rather than purely conceptual understanding.
ReevoSoftware EngineerCoding & AlgorithmsOnline AssessmentThis problem tests tree traversal techniques and greedy aggregation, requiring you to determine the minimum number of 'stones' needed to equalize all subtree sums to match a target value.
Reinforce LabsSoftware EngineerCoding & AlgorithmsOnline AssessmentThis question evaluates a candidate's ability to convert per-account net balances into a set of transfers, testing algorithmic problem solving, data-structure manipulation, and correctness under conservation invariants in transactional systems.
RemitlySoftware EngineerCoding & AlgorithmsTechnical ScreenThis question evaluates a candidate's object-oriented design and algorithmic scheduling competencies, focusing on concurrency control, fault tolerance, queue management, tie-breaking rules, and time/space complexity analysis within an elevator control system.
RemitlySoftware EngineerCoding & AlgorithmsOnsiteThis question evaluates geospatial algorithm and systems-design competencies, focusing on nearest-neighbor search, great-circle distance computation, spatial indexing, and runtime/memory trade-offs for scalable location queries.
RemitlySoftware EngineerCoding & AlgorithmsOnsiteDetermine whether two printable ASCII strings form a valid one-to-one and onto (bijective) character substitution mapping.
RemitlySoftware EngineerCoding & AlgorithmsOnsiteThis question evaluates understanding of rate-limiting logic, sliding-window time-based counting, and data structure design for tracking per-IP and per-(IP, host) request histories.
RenderSoftware EngineerCoding & AlgorithmsTechnical ScreenAggregate completed HTTP request logs across files to find the top five client IPv4 addresses, excluding auxiliary messages and applying deterministic count ties.
RenderSoftware EngineerCoding & AlgorithmsTechnical ScreenImplement an interpreter for a stack-based integer language supporting arithmetic, stack manipulation, output, and immediate error reporting with partial output preservation.
Retell AISoftware EngineerCoding & AlgorithmsTechnical ScreenThis problem tests the ability to implement efficient multi-column indexing using binary search and sorted set intersections to handle complex range queries.
Retell AISoftware EngineerCoding & AlgorithmsTechnical ScreenCompute max profit with forced trades 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.
RetoolSoftware EngineerCoding & AlgorithmsTechnical ScreenThis question evaluates understanding of randomized selection, efficient in-memory data structures, and API/state management for a fixed-capacity load balancer that must support addNode, removeNode, and uniform random routing while handling duplicates, removals, and empty-state behavior.
RevolutSoftware EngineerCoding & AlgorithmsTechnical ScreenThis question evaluates a candidate's mastery of concurrent programming and data-integrity principles, focusing on thread safety, atomic state updates, and deadlock avoidance when transferring funds between shared accounts.
RevolutSoftware EngineerCoding & AlgorithmsTechnical ScreenThis problem tests logic, integer arithmetic, and edge-case handling by requiring the distribution of a total sum into equal parts while managing remainders without using floating-point numbers.
RilletBackend EngineerCoding & AlgorithmsTechnical ScreenThis problem tests string parsing, data aggregation using a hash map, and sorting techniques.
RiotgamesSoftware EngineerCoding & AlgorithmsTechnical Screen