| 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) |
|
| --------------------------------------- |
----------------------------- |
-------------------------- |
----------------------- |
----------- |
-------- |
