| title | type |
|---|---|
Stack |
docs |
- 括号匹配问题及类似问题。第 20 题，第 921 题，第 1021 题。
- 栈的基本 pop 和 push 操作。第 71 题，第 150 题，第 155 题，第 224 题，第 225 题，第 232 题，第 946 题，第 1047 题。
- 利用栈进行编码问题。第 394 题，第 682 题，第 856 题，第 880 题。
- 单调栈。利用栈维护一个单调递增或者递减的下标数组。第 84 题，第 456 题，第 496 题，第 503 题，第 739 题，第 901 题，第 907 题，第 1019 题。
| Title | Solution | Difficulty | Time | Space | 收藏 |
|---|---|---|---|---|---|
| 20. Valid Parentheses | [Go]({{< relref "/ChapterFour/0020.Valid-Parentheses.md" >}}) | Easy | O(log n) | O(1) | |
| 42. Trapping Rain Water | [Go]({{< relref "/ChapterFour/0042.Trapping-Rain-Water.md" >}}) | Hard | O(n) | O(1) | ❤️ |
| 71. Simplify Path | [Go]({{< relref "/ChapterFour/0071.Simplify-Path.md" >}}) | Medium | O(n) | O(n) | ❤️ |
| 84. Largest Rectangle in Histogram | [Go]({{< relref "/ChapterFour/0084.Largest-Rectangle-in-Histogram.md" >}}) | Medium | O(n) | O(n) | ❤️ |
| 94. Binary Tree Inorder Traversal | [Go]({{< relref "/ChapterFour/0094.Binary-Tree-Inorder-Traversal.md" >}}) | Medium | O(n) | O(1) | |
| 103. Binary Tree Zigzag Level Order Traversal | [Go]({{< relref "/ChapterFour/0103.Binary-Tree-Zigzag-Level-Order-Traversal.md" >}}) | Medium | O(n) | O(n) | |
| 144. Binary Tree Preorder Traversal | [Go]({{< relref "/ChapterFour/0144.Binary-Tree-Preorder-Traversal.md" >}}) | Medium | O(n) | O(1) | |
| 145. Binary Tree Postorder Traversal | [Go]({{< relref "/ChapterFour/0145.Binary-Tree-Postorder-Traversal.md" >}}) | Hard | O(n) | O(1) | |
| 150. Evaluate Reverse Polish Notation | [Go]({{< relref "/ChapterFour/0150.Evaluate-Reverse-Polish-Notation.md" >}}) | Medium | O(n) | O(1) | |
| 155. Min Stack | [Go]({{< relref "/ChapterFour/0155.Min-Stack.md" >}}) | Easy | O(n) | O(n) | |
| 173. Binary Search Tree Iterator | [Go]({{< relref "/ChapterFour/0173.Binary-Search-Tree-Iterator.md" >}}) | Medium | O(n) | O(1) | |
| 224. Basic Calculator | [Go]({{< relref "/ChapterFour/0224.Basic-Calculator.md" >}}) | Hard | O(n) | O(n) | |
| 225. Implement Stack using Queues | [Go]({{< relref "/ChapterFour/0225.Implement-Stack-using-Queues.md" >}}) | Easy | O(n) | O(n) | |
| 232. Implement Queue using Stacks | [Go]({{< relref "/ChapterFour/0232.Implement-Queue-using-Stacks.md" >}}) | Easy | O(n) | O(n) | |
| 331. Verify Preorder Serialization of a Binary Tree | [Go]({{< relref "/ChapterFour/0331.Verify-Preorder-Serialization-of-a-Binary-Tree.md" >}}) | Medium | O(n) | O(1) | |
| 394. Decode String | [Go]({{< relref "/ChapterFour/0394.Decode-String.md" >}}) | Medium | O(n) | O(n) | |
| 402. Remove K Digits | [Go]({{< relref "/ChapterFour/0402.Remove-K-Digits.md" >}}) | Medium | O(n) | O(1) | |
| 456. 132 Pattern | [Go]({{< relref "/ChapterFour/0456.132-Pattern.md" >}}) | Medium | O(n) | O(n) | |
| 496. Next Greater Element I | [Go]({{< relref "/ChapterFour/0496.Next-Greater-Element-I.md" >}}) | Easy | O(n) | O(n) | |
| 503. Next Greater Element II | [Go]({{< relref "/ChapterFour/0503.Next-Greater-Element-II.md" >}}) | Medium | O(n) | O(n) | |
| 636. Exclusive Time of Functions | [Go]({{< relref "/ChapterFour/0636.Exclusive-Time-of-Functions.md" >}}) | Medium | O(n) | O(n) | |
| 682. Baseball Game | [Go]({{< relref "/ChapterFour/0682.Baseball-Game.md" >}}) | Easy | O(n) | O(n) | |
| 726. Number of Atoms | [Go]({{< relref "/ChapterFour/0726.Number-of-Atoms.md" >}}) | Hard | O(n) | O(n) | ❤️ |
| 735. Asteroid Collision | [Go]({{< relref "/ChapterFour/0735.Asteroid-Collision.md" >}}) | Medium | O(n) | O(n) | |
| 739. Daily Temperatures | [Go]({{< relref "/ChapterFour/0739.Daily-Temperatures.md" >}}) | Medium | O(n) | O(n) | |
| 844. Backspace String Compare | [Go]({{< relref "/ChapterFour/0844.Backspace-String-Compare.md" >}}) | Easy | O(n) | O(n) | |
| 856. Score of Parentheses | [Go]({{< relref "/ChapterFour/0856.Score-of-Parentheses.md" >}}) | Medium | O(n) | O(n) | |
| 880. Decoded String at Index | [Go]({{< relref "/ChapterFour/0880.Decoded-String-at-Index.md" >}}) | Medium | O(n) | O(n) | |
| 895. Maximum Frequency Stack | [Go]({{< relref "/ChapterFour/0895.Maximum-Frequency-Stack.md" >}}) | Hard | O(n) | O(n) | |
| 901. Online Stock Span | [Go]({{< relref "/ChapterFour/0901.Online-Stock-Span.md" >}}) | Medium | O(n) | O(n) | |
| 907. Sum of Subarray Minimums | [Go]({{< relref "/ChapterFour/0907.Sum-of-Subarray-Minimums.md" >}}) | Medium | O(n) | O(n) | ❤️ |
| 921. Minimum Add to Make Parentheses Valid | [Go]({{< relref "/ChapterFour/0921.Minimum-Add-to-Make-Parentheses-Valid.md" >}}) | Medium | O(n) | O(n) | |
| 946. Validate Stack Sequences | [Go]({{< relref "/ChapterFour/0946.Validate-Stack-Sequences.md" >}}) | Medium | O(n) | O(n) | |
| 1003. Check If Word Is Valid After Substitutions | [Go]({{< relref "/ChapterFour/1003.Check-If-Word-Is-Valid-After-Substitutions.md" >}}) | Medium | O(n) | O(1) | |
| 1019. Next Greater Node In Linked List | [Go]({{< relref "/ChapterFour/1019.Next-Greater-Node-In-Linked-List.md" >}}) | Medium | O(n) | O(1) | |
| 1021. Remove Outermost Parentheses | [Go]({{< relref "/ChapterFour/1021.Remove-Outermost-Parentheses.md" >}}) | Medium | O(n) | O(1) | |
| 1047. Remove All Adjacent Duplicates In String | [Go]({{< relref "/ChapterFour/1047.Remove-All-Adjacent-Duplicates-In-String.md" >}}) | Medium | O(n) | O(1) | |
| --------------------------------------- | ----------------------------- | -------------------------- | ----------------------- | ----------- | -------- |