System Design
Design data structures and APIs for real-world systems.
Foundation
Learn the invariant, apply it independently, then pass the Design checkpoint.
- LRU cache (Medium)
Checkpoint
A graded check of the core Design reasoning skills.
Design
Practice composing arrays, maps, linked structures, heaps, and counters so every public operation preserves state and meets its required complexity.
- Amount of New Area Painted Each Day (Hard)
- Design In-Memory File System (Hard)
- Design Parking System (Easy)
- Design Tic-Tac-Toe (Medium)
- Detect Squares (Medium)
- Dictionary and spell (Medium)
- Dot Product of Two Sparse Vectors (Medium)
- Exclusive Time of Functions (Medium)
- Expression Tree / Design an Expression Tree (Medium)
- Find Median from Data Stream (Hard)
- Find Servers That Handled Most Number of Requests (Hard)
- Guess the Word (Hard)
- Insert Delete GetRandom O(1) (Medium)
- Load balancer (Easy)
- Log analyzer (Easy)
- Logger Rate Limiter (Easy)
- Meeting Rooms III (Hard)
- My Calendar I (Medium)
- Phone directory (Medium)
- Random Pick Index (Medium)
- Random Pick with Weight (Medium)
- Range Module (Hard)
- Read N Characters Given Read4 II - Call Multiple Times (Hard)
- RLE Iterator (Medium)
- Sequentially Ordinal Rank Tracker (Hard)
- Snapshot Array (Medium)
- Stock Price Fluctuation (Medium)
- Tiny URL (Medium)
- Version control snapshot (Medium)