Coding & Algorithms interview questions

Showing 991–1020 of 3276 results

• Determine equality after limited swapsMedium

  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.

  DoorDashSoftware EngineerCoding & AlgorithmsTechnical Screen
• Find Each Cell's Nearest SourceMedium

  This question evaluates understanding of shortest-path computation and distance labeling in grid-based graphs, measuring competency in algorithmic problem solving and efficient traversal strategies.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Find closest value to a target in a BSTMedium

  This question evaluates understanding of binary search tree properties and numeric approximation, measuring competence in tree traversal, comparison logic, and algorithmic efficiency under input-size constraints.

  DoorDashMachine Learning EngineerCoding & AlgorithmsOnsite
• Find longest common ordered restaurant listHard

  This question evaluates a candidate's understanding of sequence algorithms, dynamic programming, and string/list manipulation by requiring computation of the longest common subsequence between two ordered lists of restaurant IDs.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Find names similar by one swapMedium

  This question evaluates string manipulation, character-frequency analysis, and algorithmic reasoning to determine near-matches under a single-character-swap constraint.

  DoorDashSoftware EngineerCoding & AlgorithmsTechnical Screen
• Find the Minimum Delivery Processing SpeedMedium

  This problem tests binary search on the answer space to find the minimum throughput capacity required to process a set of delivery orders within a fixed deadline.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Find the Minimum Parenthesis Deletions and Their PositionsMedium

  This problem tests string manipulation, stack-based parsing, and greedy logic to identify the indices of parentheses that must be removed to transform a string into a valid sequence.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Generate the next lexicographic array arrangementMedium

  This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Generate the next lexicographic array arrangement states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Identify members lacking specialty coverageMedium

  Identify members lacking specialty coverage 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.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Implement Timeout Refund WorkflowMedium

  Design and implement a stateful, idempotent refund workflow manager that safely handles gateway timeouts, retries, and duplicate requests.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Implement a consistent hashing ringEasy

  This question evaluates understanding of consistent hashing, virtual nodes, deterministic hash functions, and data structure design for efficient key-to-server mapping and dynamic membership changes.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Implement a hierarchical key-value storeMedium

  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.

  DoorDashSoftware EngineerCoding & AlgorithmsTechnical Screen
• Implement a simple service with testsMedium

  Implement a simple service with tests 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.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Implement and compare round-robin and consistent hashingMedium

  This question evaluates a candidate's ability to implement and reason about load balancing algorithms (round-robin and consistent hashing), covering competencies in data structures, hashing, concurrency, correctness, and unit testing.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Implement consistent hashing ringMedium

  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.

  DoorDashSoftware EngineerCoding & AlgorithmsTechnical Screen
• Implement dasher active-time calculatorMedium

  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.

  DoorDashSoftware EngineerCoding & AlgorithmsTechnical Screen
• Implement image carousel with comments and upvotesMedium

  This question evaluates a candidate's ability to design scalable data structures and efficient algorithms for interactive features, including API design, pagination, and consistency/concurrency handling for upvotes and per-image comment threads.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Implement round-robin load balancerMedium

  This question evaluates a candidate's ability to implement a strict round-robin load balancer with O(1) average operations while handling concurrent nextServer and update calls, health-check-driven skipping, and failure scenarios, testing competencies in data structures, concurrent programming, and fault-tolerant system behavior.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Implement string matching with follow-upMedium

  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.

  DoorDashSoftware EngineerCoding & AlgorithmsTechnical Screen
• Implement string-path file system operationsMedium

  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.

  DoorDashSoftware EngineerCoding & AlgorithmsTechnical Screen
• Minimize batches and allocate riders by timeMedium

  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.

  DoorDashMachine Learning EngineerCoding & AlgorithmsTechnical Screen
• Pooled Rideshare Earnings With Concurrent Rides and SurgeMedium

  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.

  DoorDashSoftware EngineerCoding & AlgorithmsTechnical Screen
• Select the best dasher for an orderMedium

  This problem evaluates algorithmic selection and geometric computation skills—filtering eligible dashers, calculating Euclidean distances, and applying deterministic tie-breaking—within the Coding & Algorithms domain at an implementation-level algorithmic abstraction.

  DoorDashSoftware EngineerCoding & AlgorithmsOnline Assessment
• Simulate Constant-Time Random Courier SelectionMedium

  Design a courier pool data structure that supports adding, removing, and uniformly selecting random courier IDs in average O(1) time.

  DoorDashSoftware EngineerCoding & AlgorithmsTechnical Screen
• Solve BFS grid delivery routingMedium

  This question evaluates proficiency in grid-based graph traversal and shortest-path computation, along with complexity analysis and handling dynamic changes, assessing skills in algorithm design, graph algorithms, and data structures within the Coding & Algorithms domain.

  DoorDashSoftware EngineerCoding & AlgorithmsTechnical Screen
• Solve string match and DashMart BFSMedium

  This question evaluates proficiency with string algorithms and pattern matching, assessing understanding of substring search complexity and algorithm selection within the algorithms and data structures domain, and is commonly asked to verify efficient low-level text-search implementation and time/space trade-off reasoning at a practical implementation level. The "Dash Mart" grid BFS evaluates graph traversal, state-space modeling, and shortest-path reasoning for multi-target collection tasks within graph algorithms and path-finding, and is commonly asked to measure competence in BFS-based search, state encoding and optimization strategies with a focus on practical algorithmic application and performance considerations.

  DoorDashSoftware EngineerCoding & AlgorithmsTechnical Screen
• Solve tree distance and design file systemMedium

  This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Solve tree distance and design file system states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Track the First Unique Restaurant in a StreamMedium

  This problem tests your ability to maintain stream uniqueness using a combination of a hash map and a doubly linked list to ensure constant-time operations.

  DoorDashSoftware EngineerCoding & AlgorithmsOnsite
• Validate a Shopping CartMedium

  Implement a shopping cart validation function that checks item availability, consolidates duplicate entries, verifies inventory levels, and ensures order minimums are satisfied.

  DoorDashSoftware EngineerCoding & AlgorithmsTechnical Screen
• Compute max island with constrained flipsMedium

  This question evaluates understanding of grid-based graph connectivity, connected-component labeling, and algorithmic complexity analysis (time and space) within the Coding & Algorithms domain, emphasizing practical algorithm design for large-scale inputs.

  DropboxData ScientistCoding & AlgorithmsTechnical Screen