practice a little every day, paws crossed ♡
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
- Questions
- 546
- Companies
- 11
- Topics
- 8
- Languages
Showing 481–510 of 1706 results
- DiscordMediumData ScientistCount a Character in a String
Count case-sensitive occurrences of a character in a string, including empty input and repeated matches.
Coding & AlgorithmsTechnical Screen - DiscordHardSoftware EngineerImplement User Sessionization From Event Stream
This question evaluates proficiency in stream processing, stateful sessionization, time-based aggregation, and per-user metric computation, focusing on competencies such as tracking user activity across unbounded ordered event streams and computing top-channel aggregates.
Coding & AlgorithmsTechnical Screen - DiscordMediumData ScientistReturn Words Present in Exactly One Message
Find words appearing in exactly one of two messages using set symmetric difference while clarifying tokenization and case rules.
Coding & AlgorithmsTechnical Screen - DockerMediumSoftware EngineerEvaluate an arithmetic expression
This problem tests the ability to parse and evaluate arithmetic expressions involving addition, subtraction, multiplication, and division, requiring careful handling of operator precedence and parsing multi-digit integers.
Coding & AlgorithmsTechnical ScreenStackParsingString Manipulation - DocuSignMediumSoftware EngineerCollapse runs of adjacent anagrams in a word list
Given a list of lowercase words, repeatedly delete any word that is an anagram of the word immediately before it, and return what remains in its original order. The task tests anagram comparison, reasoning about how repeated deletions interact, and producing a unique, order-preserving result.
Coding & AlgorithmsTechnical Screen - DocuSignMediumSoftware EngineerFind maximum island sum and required indices
This question evaluates grid-based graph traversal and connected-component aggregation skills, including handling positive and negative cell values, tie-breaking by row-major indices, and computing maximum component sums.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerCalculate Courier Earnings
This question evaluates algorithmic problem-solving with emphasis on temporal interval aggregation, handling overlapping events, and applying conditional rate multipliers under specified business rules.
Coding & AlgorithmsTechnical Screen - DoorDashHardSoftware EngineerCalculate Daily Driver Pay
This question evaluates event-driven time-interval processing, interval-overlap arithmetic, rate computation, and robustness to malformed, duplicate, or unordered events when aggregating a driver's pay from a day's log.
Coding & AlgorithmsTechnical Screen - DoorDashEasySoftware EngineerCompute Courier Delivery Pay
This question tests the ability to handle time intervals and calculate cumulative earnings based on overlapping delivery pay rates.
Coding & AlgorithmsTechnical ScreenArraysIntervalsGreedy - DoorDashMediumSoftware EngineerCompute Differences Between Catalog Trees
This question evaluates proficiency in tree algorithms and hierarchical data comparison, including simultaneous traversal, subtree sizing, key-based node identity, and time/space complexity reasoning, and is commonly asked to assess algorithmic problem-solving and trade-off analysis when comparing structured datasets.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerCompute Driver Pay with Double-Pay Windows
This question evaluates a candidate's ability to perform interval arithmetic and aggregation for time-based pay computations, including handling overlapping intervals, half-open boundaries, capped double-pay application, and special-case handling for canceled orders.
Coding & AlgorithmsTechnical Screen - DoorDashEasySoftware EngineerCompute Nearest Destination Distances
This problem tests your ability to use Multi-Source Breadth-First Search (BFS) to find the distance from every empty cell to the nearest destination in a grid.
Coding & AlgorithmsTechnical ScreenBFSGraphsGrid - DoorDashMediumSoftware EngineerCompute delivery times on a grid
This question evaluates understanding of graph traversal and shortest-path algorithms, grid-based pathfinding, and data structure selection for representing sparse or large grids within the Coding & Algorithms domain.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerCompute earliest arrival in time-grid
This question evaluates algorithmic problem-solving and pathfinding skills on grid-based graphs, focusing on modeling time-dependent traversal constraints and reasoning about efficient search and supporting data structures.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerCompute nearest dashmart and busiest assignments
Compute nearest dashmart and busiest assignments 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 - DoorDashMediumSoftware EngineerCompute nearest dashmart distances for queries
This question evaluates a candidate's understanding of graph traversal and shortest-path computation on grids, spatial reasoning about obstacles and sources, and the ability to analyze algorithmic scalability and complexity when answering many queries.
Coding & AlgorithmsTechnical Screen - DoorDashHardSoftware EngineerCount changed nodes between two menu trees
This problem tests recursive tree traversal and hierarchical diffing strategies to identify structural and content changes between two versions of a menu tree.
Coding & AlgorithmsTechnical ScreenTreesRecursionHash Maps - DoorDashMediumSoftware EngineerCount changed nodes in N-ary trees
This question evaluates understanding of N-ary tree data structures, structural comparison of hierarchical versions, and the ability to reason about time and space complexity when detecting added, deleted, value-changed, or reparented nodes.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerDebug round-robin, DashMap, and simple cache
This question evaluates skills in concurrent programming and stateful selection logic (round-robin load balancing), data structure invariants and debugging (custom hash map hashing vs equality, collision resolution, resizing and iterator correctness), simple in-memory caching strategies with TTL or size-based eviction, and unit test design.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerDesign a single-machine LRU cache
This question evaluates a candidate's ability to design an efficient in-memory LRU cache and apply concurrency control, covering eviction semantics, capacity management, key updates, and synchronization for thread safety.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerDesign hierarchical path store with create/set/get/remove
This question evaluates a candidate's competency in hierarchical data structures, path parsing, API semantics, error signaling, complexity analysis, and unit testing for implementing a UNIX-style key-value path store.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerDetermine equality after limited swaps
This question evaluates string manipulation and combinatorial reasoning about character swaps and anagram formation, focusing on competencies such as frequency analysis and reasoning about minimal edit operations.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerFind names similar by one swap
This question evaluates string manipulation, character-frequency analysis, and algorithmic reasoning to determine near-matches under a single-character-swap constraint.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerImplement a hierarchical key-value store
Implement a hierarchical key-value store 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 - DoorDashMediumSoftware EngineerImplement consistent hashing ring
This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Implement consistent hashing ring states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerImplement dasher active-time calculator
This question evaluates competency in time-based event processing, pairing related events, computing durations using LocalDateTime and Duration APIs, and analyzing algorithmic time and space complexity.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerImplement string matching with follow-up
A DoorDash software-engineer coding screen on string matching: implement firstIndex(T, P) in O(|T| + |P|) time and O(|P|) space using KMP, then handle follow-ups on naive vs KMP vs Rabin–Karp, Unicode and very long inputs, edge cases, wildcard ('?'/'*') matching, and simultaneous multi-pattern search via Aho–Corasick. Includes corrected, complete solutions and complexity trade-offs.
Coding & AlgorithmsTechnical Screen - DoorDashMediumSoftware EngineerImplement string-path file system operations
This question evaluates competency in designing data structures for hierarchical string-path file systems, including string parsing, stateful API semantics, validation logic, and efficient lookup/update operations.
Coding & AlgorithmsTechnical Screen - DoorDashMediumMachine Learning EngineerMinimize batches and allocate riders by time
This problem tests your ability to optimize resource scheduling by grouping tasks with overlapping time windows into the minimum number of batches, subject to capacity constraints.
Coding & AlgorithmsTechnical ScreenGreedyIntervalsBin Packing - DoorDashMediumSoftware EngineerPooled Rideshare Earnings With Concurrent Rides and Surge
Compute a pooled-ride driver's total earnings where each minute's pay scales with how many riders are currently in the car, and minutes inside non-overlapping surge windows pay double, testing sweep-line interval counting with exact half-open boundaries and 64-bit totals.
Coding & AlgorithmsTechnical Screensweep-lineintervalsarrays
Discord
DocuSign
DoorDash