資料結構設計 Design
31 題（28 題以此為主技法）
🎯 何時用
要實作有特定時間複雜度的結構（LRU、加總、隨機取、跳表）。
🧩 模板心法
組合既有結構達標：HashMap+雙向鏈表（LRU）、陣列+HashMap（O(1) 隨機）、堆+延遲刪除。
Easy 6 題
Medium 20 題
- #271Encode and Decode Strings
- #146LRU Cache
- #155Min Stack
- #173Binary Search Tree Iterator
- #380Insert Delete Get Random O(1)
- #981Time Based Key-Value Store
- #304Range Sum Query 2D Immutable
- #307Range Sum Query - Mutable
- #528Random Pick with Weight
- #535Encode and Decode TinyURL
- #622Design Circular Queue
- #707Design Linked List
- #1396Design Underground System
- #1472Design Browser History
- #1845Seat Reservation Manager
- #1993Operations On Tree
- #2013Detect Squares
- #208Implement Trie (Prefix Tree)
- #211Design Add and Search Words Data Structure
- #901Online Stock Span