堆疊 Stack
33 題（13 題以此為主技法）
🎯 何時用
需要後進先出：括號配對、運算式求值、巢狀結構解碼、路徑簡化。
🧩 模板心法
遇開符號／待處理就 push，遇閉符號／可結算就 pop 配對；用堆疊模擬遞迴或巢狀。
Easy 8 題
Medium 20 題
- #150Evaluate Reverse Polish Notation
- #227Basic Calculator II
- #71Simplify Path
- #394Decode String
- #735Asteroid Collision
- #946Validate Stack Sequences
- #1209Remove All Adjacent Duplicates In String II
- #1963Minimum Number of Swaps to Make The String Balanced
- #2390Removing Stars From a String
- #22Generate Parentheses
- #155Min Stack
- #173Binary Search Tree Iterator
- #316Remove Duplicate Letters
- #739Daily Temperatures
- #402Remove K Digits
- #456132 Pattern
- #853Car Fleet
- #901Online Stock Span
- #1472Design Browser History
- #2130Maximum Twin Sum Of A Linked List