{"id":22551737,"url":"https://github.com/lfost42/dsa-challenges","last_synced_at":"2026-04-28T11:34:05.924Z","repository":{"id":44742499,"uuid":"470821393","full_name":"lfost42/dsa-challenges","owner":"lfost42","description":"Data Structures and Algorithm Coding Challenges","archived":false,"fork":false,"pushed_at":"2022-11-03T22:40:16.000Z","size":238,"stargazers_count":1,"open_issues_count":0,"forks_count":2,"subscribers_count":1,"default_branch":"main","last_synced_at":"2025-03-28T10:13:50.126Z","etag":null,"topics":["data-structures-and-algorithms","leetcode-js","python3"],"latest_commit_sha":null,"homepage":"","language":"JavaScript","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":null,"status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/lfost42.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":null,"code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null}},"created_at":"2022-03-17T02:29:03.000Z","updated_at":"2023-05-02T03:31:38.000Z","dependencies_parsed_at":"2022-08-26T02:42:30.292Z","dependency_job_id":null,"html_url":"https://github.com/lfost42/dsa-challenges","commit_stats":null,"previous_names":["lfost42/dsa-challenges"],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/lfost42/dsa-challenges","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/lfost42%2Fdsa-challenges","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/lfost42%2Fdsa-challenges/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/lfost42%2Fdsa-challenges/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/lfost42%2Fdsa-challenges/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/lfost42","download_url":"https://codeload.github.com/lfost42/dsa-challenges/tar.gz/refs/heads/main","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/lfost42%2Fdsa-challenges/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":286080680,"owners_count":32379368,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2026-04-28T11:25:28.583Z","status":"ssl_error","status_checked_at":"2026-04-28T11:25:05.435Z","response_time":56,"last_error":"SSL_connect returned=1 errno=0 peeraddr=140.82.121.5:443 state=error: unexpected eof while reading","robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":false,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["data-structures-and-algorithms","leetcode-js","python3"],"created_at":"2024-12-07T17:14:08.355Z","updated_at":"2026-04-28T11:34:05.906Z","avatar_url":"https://github.com/lfost42.png","language":"JavaScript","funding_links":[],"categories":[],"sub_categories":[],"readme":"# Data Structures and Algorithms\n\nI had attempted these in C# and JavaScript but alas, my career decided I was going to lead with Python so hwere we are!\n\nSource for the following list of challenges: https://www.techinterviewhandbook.org/best-practice-questions/\n\nFree source for learning to solve challenges - https://neetcode.io\n\n## Sequences\n\n|     |     |     |       |          |          |\n| --- | --- | --- | ----- | -------- | ----- |\n| py \u0026#9744; | cs \u0026#9745; | 1 | [Two Sum](https://leetcode.com/problems/two-sum/) | [py](.python/leet/1-two-sum.py) [cs](./leet/1-two-sum.cs) | Easy |\n| py \u0026#9744; | cs \u0026#9745; | 2 | [Contains Duplicate](https://leetcode.com/problems/contains-duplicate/) | [py](./python/leet/2-contains-duplicate.py) [cs](./leet/2-contains-duplicate.cs) | Easy |\n| py \u0026#9744; | cs \u0026#9745; | 3 | [Best Time to Buy and Sell Stock](https://leetcode.com/problems/best-time-to-buy-and-sell-stock/) | [py](./python/leet/3-best-time-to-buy-and-sell-stock.py) [cs](./leet/3-best-time-to-buy-and-sell-stock.cs) | Easy |\n| py \u0026#9744; | cs \u0026#9745; | 4 | [Valid Anagram](https://leetcode.com/problems/valid-anagram/) | [py](./python/leet/4-valid-anagram.py) [cs](./leet/4-valid-anagram.cs) | Easy |\n| py \u0026#9744; | cs \u0026#9745; | 5 | [Valid Parentheses](https://leetcode.com/problems/valid-parentheses/) | [py](./python/leet/5-valid-parentheses.py) [cs](./leet/5-valid-parentheses.cs) | Easy |\n| py \u0026#9744; | cs \u0026#9745; | 6 | [Maximum Subarray](https://leetcode.com/problems/maximum-subarray/) | [py](./python/leet/6-maximum-subarray.py) [cs](./leet/6-maximum-subarray.cs) | Easy |\n| py \u0026#9744; | cs \u0026#9745; | 7 | [Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self) | [py](./leet/7-product-of-array-except-self.py) [cs](./leet/7-product-of-array-except-self.cs) | Medium |\n| py \u0026#9744; | cs \u0026#9745; | 8 | [3Sum](https://leetcode.com/problems/3sum/) | [py](./python/leet/8-3sum.py) [cs](./leet/8-3sum.cs) | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 9 | [Merge Intervals](https://leetcode.com/problems/merge-intervals/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 10 | [Group Anagrams](https://leetcode.com/problems/group-anagrams/) | | Medium |\n\n## Linked Lists, Strings, Matrix\n\n|     |     |     |       |          |          |\n| --- | --- | --- | ----- | -------- | ----- |\n| py \u0026#9744; | cs \u0026#9744; | 11 | [Reverse a Linked List](https://leetcode.com/problems/reverse-linked-list/) | | Easy |\n| py \u0026#9744; | cs \u0026#9744; | 12 | [Detect Cycle in a Linked List](https://leetcode.com/problems/linked-list-cycle/) | | Easy |\n| py \u0026#9744; | cs \u0026#9744; | 13 | [Container With Most Water](https://leetcode.com/problems/container-with-most-water/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 14 | [Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 15 | [Longest Repeating Character Replacement](https://leetcode.com/problems/longest-repeating-character-replacement/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 16 | [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 17 | [Number of Islands](https://leetcode.com/problems/number-of-islands/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 18 | [Remove Nth Node From End Of List](https://leetcode.com/problems/remove-nth-node-from-end-of-list/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 19 | [Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 20 | [Pacific Atlantic Water Flow](https://leetcode.com/problems/pacific-atlantic-water-flow/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 21 | [Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring/) | | Hard |\n\n## Trees, Graphs, Heaps\n\n|     |     |     |       |          |          |\n| --- | --- | --- | ----- | -------- | ----- |\n| py \u0026#9744; | cs \u0026#9744; | 22 | [Invert/Flip Binary Tree](https://leetcode.com/problems/invert-binary-tree/) | | Easy |\n| py \u0026#9744; | cs \u0026#9744; | 23 | [Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 24 | [Non-overlapping Intervals](https://leetcode.com/problems/non-overlapping-intervals/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 25 | [Construct Binary Tree from Preorder and Inorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 26 | [Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 27 | [Clone Graph](https://leetcode.com/problems/clone-graph/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 28 | [Course Schedule](https://leetcode.com/problems/course-schedule/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 29 | [Serialize and Deserialize Binary Tree](https://leetcode.com/problems/serialize-and-deserialize-binary-tree/) | | Hard |\n| py \u0026#9744; | cs \u0026#9744; | 30 | [Binary Tree Maximum Path Sum](https://leetcode.com/problems/binary-tree-maximum-path-sum/) | | Hard |\n\n## Advanced Data Structures\n\n|     |     |     |       |          |          |\n| --- | --- | --- | ----- | -------- | ----- |\n| py \u0026#9744; | cs \u0026#9744; | 31 | [Subtree of Another Tree](https://leetcode.com/problems/subtree-of-another-tree/) | | Easy |\n| py \u0026#9744; | cs \u0026#9744; | 32 | [Lowest Common Ancestor of BST](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/) | | Easy |\n| py \u0026#9744; | cs \u0026#9744; | 33 | [Implement Trie (Prefix Tree)](https://leetcode.com/problems/ |\n| py \u0026#9744; | cs \u0026#9744; | 34 | [Add and Search Word](https://leetcode.com/problems/add-and-search-word-data-structure-design/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 35 | [Kth Smallest Element in a BST](https://leetcode.com/problems/kth-smallest-element-in-a-bst/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 36 | [Merge K Sorted Lists](https://leetcode.com/problems/merge-k-sorted-lists/) | | Hard |\n| py \u0026#9744; | cs \u0026#9744; | 37 | [Find Median from Data Stream](https://leetcode.com/problems/find-median-from-data-stream/) | | Hard |\n| py \u0026#9744; | cs \u0026#9744; | 38 | [Insert Interval](https://leetcode.com/problems/insert-interval/) | \n| py \u0026#9744; | cs \u0026#9744; | 39 | [Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 40 | [Word Search II](https://leetcode.com/problems/word-search-ii/) | | Hard |\n\n## Dynamic Programming\n\n|     |     |     |       |          |          |\n| --- | --- | --- | ----- | -------- | ----- |\n| py \u0026#9744; | cs \u0026#9744; | 41 | [Climbing Stairs](https://leetcode.com/problems/climbing-stairs/) | | Easy |\n| py \u0026#9744; | cs \u0026#9744; | 42 | [Coin Change](https://leetcode.com/problems/coin-change/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 43 | [Longest Increasing Subsequence](https://leetcode.com/problems/longest-increasing-subsequence/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 44 | [Combination Sum](https://leetcode.com/problems/combination-sum-iv/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 45 | [House Robber](https://leetcode.com/problems/house-robber/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 46 | [House Robber II](https://leetcode.com/problems/house-robber-ii/) | \n| py \u0026#9744; | cs \u0026#9744; | 47 | [Decode Ways](https://leetcode.com/problems/decode-ways/) | | Medium \n| py \u0026#9744; | cs \u0026#9744; | 48 | [Unique Paths](https://leetcode.com/problems/unique-paths/) | | \n| py \u0026#9744; | cs \u0026#9744; | 49 | [Jump Game](https://leetcode.com/problems/jump-game/) | | Medium |\n| py \u0026#9744; | cs \u0026#9744; | 50 | [Word Break Problem](https://leetcode.com/problems/word-break/) | | Medium |\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Flfost42%2Fdsa-challenges","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Flfost42%2Fdsa-challenges","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Flfost42%2Fdsa-challenges/lists"}