61 Object Oriented Programming questions that open without a paid plan — full statement, editor and judged verdict. Easiest first.
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| Question | Company | Difficulty | Reported |
|---|---|---|---|
| Durable Key-Value Store Serialization | OpenAI / Airbnb / Amazon / Confluent / Databricks / Google / LinkedIn / Pinterest / Snapchat / Snowflake | Easy | Nov 08, 2025 |
| Rate Limiter | Stripe / Amazon / Atlassian / Google / Microsoft / Pinterest / Roblox / Snapchat / Snowflake / Waymo | Easy | Dec 06, 2025 |
| React UI: Multi-select Color Dropdown and Selected Properties Table | Brex | Easy | — |
| Trie-Based Autocomplete | Oracle | Easy | Sep 15, 2025 |
| Sliding-Window Rate Limiter III | Rippling / Amazon / Atlassian / LinkedIn / Microsoft / NVIDIA / Oracle / Reddit / Roblox / Waymo / xAI | Medium | — |
| Banking System with Payments and Account Merging | Ramp / Anthropic / Capital One / Coinbase / HubSpot / Instacart | Medium | — |
| LRU Cache III | Verkada / Amazon / ByteDance / Goldman Sachs / Lyft / Rokt | Medium | — |
| Implement an LRU cache with O(1) ops | Onemain Financial / Anthropic / Google / LinkedIn / Microsoft | Medium | — |
| Recipe Manager | Coinbase / Anthropic / HubSpot / Ramp | Medium | Dec 15, 2025 |
| Cloud Storage System | Coinbase / Ebay / HubSpot | Medium | — |
| Design Key-Value Store with Transactions | Snowflake / Applied Intuition / Lyft | Medium | Feb 26, 2026 |
| In-Memory Database | Coinbase / Anthropic / Applied Intuition | Medium | Apr 28, 2026 |
| In-Memory Unix File System | Perplexity / Harvey / Shopify | Medium | Jun 15, 2026 |
| Parallel Courses III | Snowflake / ByteDance / Netflix | Medium | Jun 15, 2026 |
| Binary Search Tree Iterator | Apple / Microsoft | Medium | Jan 29, 2026 |
| Contiguous Memory Allocator II | OpenAI / ByteDance | Medium | Jun 11, 2026 |
| Design Lazy Array | Databricks / Amazon | Medium | Apr 13, 2026 |
| In-Memory Database with SQL Operations | OpenAI / Airbnb | Medium | Nov 07, 2025 |
| Query Pagination | Coinbase / Lyft | Medium | Feb 04, 2026 |
| Snake Game | Atlassian / Amplitude | Medium | Oct 02, 2025 |
| Task Management System III | Coinbase / Instacart | Medium | — |
| API Call and Data Processing | PayPal | Medium | — |
| Banking System with Transaction Activity | Capital One | Medium | — |
| Basic Calculator with Operators, Variables, and Functions | Tesla | Medium | Jul 24, 2025 |
| Body-Temperature Measurement Classes | Oracle | Medium | Jan 15, 2025 |
| Commodity Price Checkpoints | Atlassian | Medium | Sep 12, 2025 |
| Credit Tracker with Expiring Credits | Perplexity | Medium | Aug 09, 2025 |
| Delivery Cost Calculate | Rippling | Medium | Jun 18, 2026 |
| Design a Recommender System Based on Price and Distance | Stubhub | Medium | — |
| Design an In-Memory Cloud Storage System (Incremental Levels) | Tradedesk | Medium | — |
| Design Spreadsheet Undo and Redo | Airtable | Medium | — |
| Deterministic Function Wrapper with Caching | Squarepoint | Medium | — |
| Event Bus with Emit, Subscribe, and Unsubscribe | Tesla | Medium | Jul 04, 2025 |
| Extend Queue: Min-Size & Min-Sum Selector | Goldman Sachs | Medium | Jun 09, 2025 |
| File Management System | Oracle | Medium | Sep 16, 2025 |
| Find Duplicate Files | Anthropic | Medium | Jun 10, 2026 |
| Frontend Practical Coding — Work Against a Provided API | Vanta | Medium | Jul 24, 2025 |
| Hot Air Balloon Festival Simulation | Optiver | Medium | Sep 09, 2025 |
| Implement 2048 Game Logic | Glean | Medium | Mar 01, 2026 |
| Implement a Custom Vector Using Metaprogramming | Squarepoint | Medium | — |
| Implement a Generic Stack in C++ | Arista | Medium | — |
| Implement a Mini Spreadsheet with Get/Set, Row Printing, and Add Formulas with Cycle Handling | Sigmacomputing | Medium | — |
| Implement a Text Editor | Rokt | Medium | — |
| Implement Game Metadata Lookups | Discord | Medium | Apr 03, 2026 |
| Key-Value Store with getLast | SoFi | Medium | Jul 14, 2025 |
| Kubernetes Controller for Pod Balance | IBM | Medium | Aug 25, 2025 |
| Logger System | Rippling | Medium | Jun 09, 2026 |
| Mobile Table View Timer App | Robinhood | Medium | Aug 2025 |
| Org Tree Lowest Common Department | Atlassian | Medium | Feb 15, 2026 |
| Priority Expiry LRU Cache | Tesla | Medium | Aug 19, 2025 |
| Rate Limit an API During a Traffic Attack | Render | Medium | 🆕 Sep 17, 2026 |
| Report Chain | Medium | Feb 17, 2026 | |
| Satellite Message Propagation | Optiver | Medium | Aug 05, 2025 |
| Sparse Matrix Left- and Right-Multiply Vector | Waymo | Medium | Sep 29, 2025 |
| Tagged Command Undo | Netflix | Medium | Apr 30, 2026 |
| ToDo List with Task Dependencies | Perplexity | Medium | May 26, 2026 |
| Treatment Frequency Scheduler | Oracle | Medium | Sep 15, 2025 |
| Banking System with Transfers, Top Spenders, Delayed Payments, and Account Merging | Circle | Hard | — |
| Composable Event Recommendation Campaign Engine (Flexible Filters + Ranking + Fallback) | Stubhub | Hard | — |
| Design and Solve a Rotatable Jigsaw Puzzle | Asana | Hard | Apr 13, 2026 |
| Track Best Bid/Ask with Cancellations | Akuna Capital | Hard | Sep 22, 2025 |