> For the complete documentation index, see [llms.txt](https://jinjunliu.gitbook.io/notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jinjunliu.gitbook.io/notes/leetcode.md). # Leetcode This notebook records the Leetcode problems I have solved. ### Solved Leetcode Problems In chronological order: | Date | Problem | type | | ---------- | ----------------------------------------------------------------------------- | -------------------- | | 5/15/2022 | 3Sum, 3Sum Closest | array | | 5/16/2022 | Longest Substring Without Repeating Characters, Longest Palindromic Substring | string | | 5/17/2022 | Container With Most Water, Remove Nth Node From End of List | two pointers | | 5/18/2022 | Add Two Numbers, Merge Two Sorted Lists | linked list | | 5/19/2022 | Valid Parentheses | stack | | 5/20/2022 | Simplify Path | stack | | 5/21/2022 | Binary Tree Inorder Traversal, Unique Binary Search Trees | tree | | 5/27/2022 | Generate Parentheses | dynamic programming | | 7/27/2022 | Letter Combinations of a Phone Number | Backtracking | | 7/29/2022 | Combination Sum | Backtracking | | 8/16/2022 | Validate Binary Search Tree | DFS | | 8/17/2022 | Recover Binary Search Tree | DFS | | 8/18/2022 | Same Tree, Symmetric Tree | BFS | | 8/19/2022 | Search in Rotated Sorted Array | Binary Search | | 8/20/2022 | Linked List Cycle II | Linked List | | 8/22/2022 | First Bad Version, Sqrt(x), Search Insert Position | Binary Search | | 8/25/2022 | Capacity to Ship Packages Within D Days | Binary Search | | 8/27/2022 | Reverse Integer, Palindrome Number, Two Sum | Math, Hash Table | | 9/8/2022 | Group Anagrams, Merge Intervals | Sorting | | 9/10/2022 | Add Binary | Bit Manipulation | | 9/17/2022 | Longest Consecutive Sequence | Union Find | | 01/22/2024 | Merge Strings Alternately, Reverse Words in a String | String | | 01/23/2024 | Greatest Common Divisor of Strings, Product of Array Except Self | String, Array | | 01/24/2024 | Kids With the Greatest Number of Candies, Increasing Triplet Subsequence | Array | | 08/03/2024 | Reverse Vowels of a String | Two Pointers | | 05/30/2025 | String Compression | Two Pointers, String | | 05/30/2025 | Move Zeros | Two Pointers, Array | In numerical order: | Number | Title | Difficulty | | ------ | ------------------------------------------------------------------------------------------------------------------------------- | ---------- | | 1 | [Two Sum](https://leetcode.com/problems/two-sum/) | Easy | | 2 | [Add Two Numbers](https://leetcode.com/problems/add-two-numbers/) | Medium | | 3 | [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/) | Medium | | 5 | [Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring/) | Medium | | 7 | [Reverse Integer](https://leetcode.com/problems/reverse-integer/) | Medium | | 9 | [Palindrome Number](https://leetcode.com/problems/palindrome-number/) | Easy | | 11 | [Container With Most Water](https://leetcode.com/problems/container-with-most-water/) | Medium | | 15 | [3Sum](https://leetcode.com/problems/3sum/) | Medium | | 16 | [3Sum Closest](https://leetcode.com/problems/3sum-closest/) | Medium | | 17 | [Letter Combinations of a Phone Number](https://leetcode.com/problems/letter-combinations-of-a-phone-number/) | Medium | | 19 | [Remove Nth Node From End of List](https://leetcode.com/problems/remove-nth-node-from-end-of-list/) | Medium | | 20 | [Valid Parentheses](https://leetcode.com/problems/valid-parentheses/) | Easy | | 21 | [Merge Two Sorted Lists](https://leetcode.com/problems/merge-two-sorted-lists/) | Easy | | 22 | [Generate Parentheses](https://leetcode.com/problems/generate-parentheses/) | Medium | | 33 | [Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/) | Medium | | 35 | [Search Insert Position](https://leetcode.com/problems/search-insert-position/) | Easy | | 39 | [Combination Sum](https://leetcode.com/problems/combination-sum/) | Medium | | 49 | [Group Anagrams](https://leetcode.com/problems/group-anagrams/) | Medium | | 56 | [Merge Intervals](https://leetcode.com/problems/merge-intervals/) | Medium | | 67 | [Add Binary](https://leetcode.com/problems/add-binary/) | Easy | | 69 | [Sqrt(x)](https://leetcode.com/problems/sqrtx/) | Easy | | 71 | [Simplify Path](https://leetcode.com/problems/simplify-path/) | Medium | | 94 | [Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal/) | Easy | | 96 | [Unique Binary Search Trees](https://leetcode.com/problems/unique-binary-search-trees/) | Medium | | 98 | [Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree/) | Medium | | 99 | [Recover Binary Search Tree](https://leetcode.com/problems/recover-binary-search-tree/) | Medium | | 100 | [Same Tree](https://leetcode.com/problems/same-tree/) | Easy | | 101 | [Symmetric Tree](https://leetcode.com/problems/symmetric-tree/) | Easy | | 128 | [Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence/) | Medium | | 142 | [Linked List Cycle II](https://leetcode.com/problems/linked-list-cycle-ii/) | Medium | | 151 | [Reverse Words in a String](https://leetcode.com/problems/reverse-words-in-a-string/) | Medium | | 238 | [Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self/) | Medium | | 278 | [First Bad Version](https://leetcode.com/problems/first-bad-version/) | Easy | | 283 | [Move Zeros](https://leetcode.com/problems/move-zeroes/) | Easy | | 334 | [Increasing Triplet Subsequence](https://leetcode.com/problems/increasing-triplet-subsequence/) | Medium | | 345 | [Reverse Vowels of a String](https://leetcode.com/problems/reverse-vowels-of-a-string/) | Easy | | 443 | [String Compression](https://leetcode.com/problems/string-compression/) | Medium | | 1011 | [Capacity to Ship Packages Within D Days](https://leetcode.com/problems/capacity-to-ship-packages-within-d-days/) | Medium | | 1071 | [Greatest Common Divisor of Strings](https://leetcode.com/problems/greatest-common-divisor-of-strings/) | Easy | | 1431 | [Kids With the Greatest Number of Candies](https://leetcode.com/problems/kids-with-the-greatest-number-of-candies/) | Easy | | 1768 | [Merge Strings Alternately](https://leetcode.com/problems/merge-strings-alternately/) | Easy | ### Resources * * [Coding Interview Preparation - Kaiyu Zheng](https://github.com/jinjunliu/notes/blob/master/docs/Coding_Interview_Preparation_document.pdf)