Coding questions

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1. Coding questions · DoorDash

   Implement a gig worker payout calculator

   This question evaluates skills in data modeling, time-series event handling, business-rule implementation, monetary rounding/precision, and idempotent processing, with an emphasis on SQL and Python proficiency for data manipulation.

2. Coding questions · OpenAI

   Implement a GPU credit manager

   This question evaluates understanding of concurrent resource management, advanced data structures for top-K and per-user queries, enforcement of caps and expirations, and algorithmic complexity guarantees while maintaining atomicity under concurrent operations.

3. Coding questions · Paradromics

   Implement 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.

4. Coding questions · DoorDash

   Implement 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.

5. Coding questions · DocuSign

   Implement a key-value CRUD store

   This question evaluates understanding of core data structures, API design, complexity analysis, and edge-case handling for an in-memory key–value CRUD store, and falls under the Coding & Algorithms domain while testing both practical implementation skills and conceptual reasoning about time/space trade-offs.

6. Coding questions · Anthropic

   Implement a Least-Recently-Used Cache

   This question evaluates a candidate's ability to design and implement an efficient in-memory cache with eviction behavior, testing understanding of data structure selection, state management, and time/space complexity under capacity constraints.

7. Coding questions · TikTok

   Implement a match-3 board resolver

   TikTok software-engineer technical-screen coding question: implement a match-3 board resolver over an m×n grid. Repeatedly remove connected horizontal/vertical runs of three or more equal cells, apply gravity so survivors fall and blanks rise to the top, cascade until the board is stable, and return the final board plus the total cells removed. It tests grid simulation, run detection via linear scans, per-column gravity, termination reasoning, and time/space complexity analysis.

8. Coding questions · Zipline

   Implement a Maximum-Tracking Stack

   This question evaluates competency in data structure design and algorithmic analysis, focusing on stack operations augmented with maximum-tracking and correctness when multiple maximal elements and ordering constraints are present.

9. Coding questions · OpenAI

   Implement a memory allocator with malloc/free

   This question evaluates understanding of memory allocator concepts including malloc/free semantics, contiguous allocation, fragmentation handling, coalescing of adjacent free blocks, pointer validation, and data-structure choices for efficient allocation.

10. Coding questions · Cursor

    Implement a Merkle-tree repo diff

    This question evaluates a candidate's understanding of Merkle trees, filesystem-aware hashing, directory traversal, and diff algorithms for detecting file-level changes.

11. Coding questions · Pinterest

    Implement a min-heap column allocator

    This question evaluates a candidate's competency in data structures (priority queues/min-heaps), online algorithm design for stream processing, and complexity and memory analysis.

12. Coding questions · Read.Ai

    Implement a per-user API rate limiter

    This question evaluates the ability to implement per-user API rate limiting, testing competency in time-windowed request accounting, per-entity state management, and designing efficient data structures for time-based constraints.

13. Coding questions · OpenAI

    Implement a persistent sharded key-value store

    This question evaluates understanding of persistent storage and file-based sharding, including on-disk layout, record serialization, indexing strategies for locating the latest value per key, shard rollover, and recovery from partial or corrupt tails.

14. Coding questions · Instacart

    Implement a pivot table transformation

    This question evaluates competency in data transformation and aggregation, specifically pivot operations, time-based grouping, null handling, dimensionality reduction (top‑K/OTHER), scalability for large datasets, and expressing solutions in both Python (pandas or pure) and SQL within the Data Manipulation (SQL/Python) domain.

15. Coding questions · Anthropic

    Implement a recency-eviction bounded cache

    This question evaluates understanding of recency-based eviction (LRU) cache design and proficiency with core data structures and algorithmic complexity, including achieving amortized O(1) operations and O(N) space.

16. Coding questions · Aurora

    Implement a reference-counted smart pointer

    This question evaluates understanding of C++ resource management, ownership semantics, RAII, and reference counting implementation within the coding and algorithms domain, emphasizing pointer semantics and object lifetime.

17. Coding questions · Uber

    Implement a Referral Revenue Tracker

    This question evaluates proficiency with data structures and algorithms for hierarchical aggregation and ranking, assessing skills such as maintaining recursive subtree aggregates, handling dynamic inserts, and executing efficient top-k queries; it is in the Coding & Algorithms domain and tests practical application of in-memory data structure design. It is commonly asked to evaluate the ability to design scalable, low-latency in-memory systems that preserve aggregate values across referral trees and support fast query operations while reasoning about time and space complexity trade-offs.

18. Coding questions · Tml

    Implement a Resizable Deque

    This question evaluates proficiency in data structures and array-based implementations, specifically building a resizable double-ended queue (deque) backed by a circular array and understanding amortized O(1) operation costs.

19. Coding questions · Anthropic

    Implement a same-host web crawler

    This question evaluates a candidate's competency in graph traversal and state management, URL parsing and validation, duplicate detection and cycle handling, and concurrent coordination with per-host rate limiting.

20. Coding questions · OpenAI

    Implement a serializable key-value store

    This question evaluates competency in implementing robust serialization and in-memory data structures, covering binary format design, handling arbitrary bytes and Unicode, correctness across edge cases (empty state, large keys/values, overwrites, deletions), input validation and failure recovery, complexity analysis, and unit testing.

21. Coding questions · Coinbase

    Implement a Simple Banking Ledger

    This question evaluates competence in designing an efficient, stateful ledger API and associated data structures, emphasizing correctness under invalid inputs, performance at scale, integer overflow handling, unit testing for edge cases, and transactional (atomic batch) behavior.

22. Coding questions · OpenAI

    Implement a Simulated Memory Allocator

    This question evaluates a candidate's understanding of dynamic memory management, low-level resource handling, and algorithmic data structures (e.g., segregated free lists, interval/balanced trees, buddy system) with attention to alignment, internal/external fragmentation, and block coalescing.

23. Coding questions · Roblox

    Implement a sliding-window rate limiter

    Evaluates the candidate's ability to design and implement an in-memory sliding-window rate limiter enforcing per-user and per-game constraints, focusing on correct request-acceptance semantics and efficient timestamp eviction; Category/domain: Coding & Algorithms; Level of abstraction: component-level algorithm and data-structure implementation.

24. Coding questions · Microsoft

    Implement a Snapshot Set Iterator

    This question evaluates proficiency in data structure design, iterator semantics, and managing snapshot consistency for mutable collections. It is commonly asked in the Coding & Algorithms domain to assess practical implementation skills and conceptual understanding of producing an iterator that reflects the set's state at the moment iterator() is called, testing practical application with reasoning about immutability, consistency, and complexity.