https://github.com/cheatsheet1999/CloudCollection

Notes for Software Engineers on infrastructure and distributed systems. Covers common data structure and algorithms, web concepts, and more!
https://github.com/cheatsheet1999/CloudCollection
backend cloudinfrastructure data-structures distributed-systems frontend infrastructure interview
Last synced: 28 days ago
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Notes for Software Engineers on infrastructure and distributed systems. Covers common data structure and algorithms, web concepts, and more!
Host: GitHub
URL: https://github.com/cheatsheet1999/CloudCollection
Owner: cheatsheet1999
Created: 2021-06-16T04:02:44.000Z (almost 5 years ago)
Default Branch: main
Last Pushed: 2026-05-15T08:15:57.000Z (30 days ago)
Last Synced: 2026-05-15T10:30:58.693Z (29 days ago)
Topics: backend, cloudinfrastructure, data-structures, distributed-systems, frontend, infrastructure, interview
Language: Go
Homepage:
Size: 23.3 MB
Stars: 2,776
Watchers: 100
Forks: 329
Open Issues: 41
Metadata Files:
- Readme: README.md
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awesome-github-projects - CloudCollection - Notes for Software Engineers on infrastructure and distributed systems. Covers common data structure and algorithms, web concepts, and more! ⭐2,778 `Go` 🔥 (⚙️ Backend & APIs)
README

          # CloudCollection 📚

A comprehensive collection of algorithm solutions, system design materials, and modern C++ tutorials. Perfect for interview preparation, learning, and reference.

---

## 🧮 Data Structures & Algorithms

Organized by topic and difficulty level, with detailed solutions and explanations.

### 📊 Array & Two Pointers

[0001. Two Sum](/Data%20Structure%20and%20Algorithms/LeetCode/0001.%20Two%20Sum.md)  

[0011. Container With Most Water](/Data%20Structure%20and%20Algorithms/LeetCode/0011.%20Container%20With%20Most%20Water.md)  

[0015. 3Sum](/Data%20Structure%20and%20Algorithms/LeetCode/0015.%203Sum.md)  

[0016. 3Sum Closest](/Data%20Structure%20and%20Algorithms/LeetCode/0016.%203Sum%20Closest.md)  

[0018. 4Sum](/Data%20Structure%20and%20Algorithms/LeetCode/0018.%204Sum.md)  

[0027. Remove Element](/Data%20Structure%20and%20Algorithms/LeetCode/0027.%20Remove%20Element.md)  

[0031. Next Permutation](/Data%20Structure%20and%20Algorithms/LeetCode/0031.%20Next%20Permutation.md)  

[0042. Trapping Rain Water](/Data%20Structure%20and%20Algorithms/LeetCode/0042.%20Trapping%20Rain%20Water.md)  

[0045. Jump Game II](/Data%20Structure%20and%20Algorithms/LeetCode/0045.%20Jump%20Game%20II.md)  

[0055. Jump Game](/Data%20Structure%20and%20Algorithms/LeetCode/0055.%20Jump%20Game.md)  

[0056. Merge Intervals](/Data%20Structure%20and%20Algorithms/LeetCode/0056.%20Merge%20Intervals.md)  

[0057. Insert Interval](/Data%20Structure%20and%20Algorithms/LeetCode/0057.%20Insert%20Interval.md)  

[0066. Plus One](/Data%20Structure%20and%20Algorithms/LeetCode/0066.%20Plus%20One.md)  

[0075. Sort Colors](/Data%20Structure%20and%20Algorithms/LeetCode/0075.%20Sort%20Colors.md)  

[0088. Merge Sorted Array](/Data%20Structure%20and%20Algorithms/LeetCode/0088.%20Merge%20Sorted%20Array.md)  

[0189. Rotate Array](/Data%20Structure%20and%20Algorithms/LeetCode/0189.%20Rotate%20Array.md)  

[0238. Product of Array Except Self](/Data%20Structure%20and%20Algorithms/LeetCode/0238.%20Product%20of%20Array%20Except%20Self.md)  

[0283. Move Zeroes](/Data%20Structure%20and%20Algorithms/LeetCode/0283.%20Move%20Zeroes.md)  

[0347. Top K Frequent Elements](/Data%20Structure%20and%20Algorithms/LeetCode/0347.%20Top%20K%20Frequent%20Elements.md)  

[0349. Intersection of Two Arrays](/Data%20Structure%20and%20Algorithms/LeetCode/0349.%20Intersection%20of%20Two%20Arrays.md)  

[0350. Intersection of Two Arrays II](/Data%20Structure%20and%20Algorithms/LeetCode/0350.%20Intersection%20of%20Two%20Arrays%20II.md)  

[0605. Can Place Flowers](/Data%20Structure%20and%20Algorithms/LeetCode/0605.%20Can%20Place%20Flowers.md)  

[0724. Find Pivot Index](/Data%20Structure%20and%20Algorithms/LeetCode/0724.%20Find%20Pivot%20Index.md)  

[1010. Pairs of Songs With Total Durations Divisible by 60](/Data%20Structure%20and%20Algorithms/LeetCode/1010.%20Pairs%20of%20Songs%20With%20Total%20Durations%20Divisible%20by%2060.md)  

[1299. Replace Elements with Greatest Element on Right Side](/Data%20Structure%20and%20Algorithms/LeetCode/1299.%20Replace%20Elements%20with%20Greatest%20Element%20on%20Right%20Side.md)  

[1984. Minimum Difference Between Highest and Lowest of K Scores](/Data%20Structure%20and%20Algorithms/LeetCode/1984.%20Minimum%20Difference%20Between%20Highest%20and%20Lowest%20of%20K%20Scores.md)  

[Two Sum II - Input Array Is Sorted](/Data%20Structure%20and%20Algorithms/LeetCode/Two%20Sum%20II%20-%20Input%20Array%20Is%20Sorted.md)  

  

### 📝 String

[0003. Longest Substring Without Repeating Characters](/Data%20Structure%20and%20Algorithms/LeetCode/0003.%20Longest%20Substring%20Without%20Repeating%20Characters.md)  

[0005. Longest Palindromic Substring](/Data%20Structure%20and%20Algorithms/LeetCode/0005.%20Longest%20Palindromic%20Substring.md)  

[0006. Zigzag Conversion](/Data%20Structure%20and%20Algorithms/LeetCode/0006.%20Zigzag%20Conversion.md)  

[0012. Integer to Roman](/Data%20Structure%20and%20Algorithms/LeetCode/0012.%20Integer%20to%20Roman.md)  

[0013. Roman to Integer](/Data%20Structure%20and%20Algorithms/LeetCode/0013.%20Roman%20to%20Integer.md)  

[0014. Longest Common Prefix](/Data%20Structure%20and%20Algorithms/LeetCode/0014.%20Longest%20Common%20Prefix.md)  

[0020. Valid Parentheses](/Data%20Structure%20and%20Algorithms/LeetCode/0020.%20Valid%20Parentheses.md)  

[0028. Find the Index of the First Occurrence in a String](/Data%20Structure%20and%20Algorithms/LeetCode/0028.%20Find%20the%20Index%20of%20the%20First%20Occurrence%20in%20a%20String.md)  

[0038. Count and Say](/Data%20Structure%20and%20Algorithms/LeetCode/0038.%20Count%20and%20Say.md)  

[0043. Multiply Strings](/Data%20Structure%20and%20Algorithms/LeetCode/0043.%20Multiply%20Strings.md)  

[0058. Length of Last Word](/Data%20Structure%20and%20Algorithms/LeetCode/0058.%20Length%20of%20Last%20Word.md)  

[0071. Simplify Path](/Data%20Structure%20and%20Algorithms/LeetCode/0071.%20Simplify%20Path.md)  

[0125. Valid Palindrome](/Data%20Structure%20and%20Algorithms/LeetCode/0125.%20Valid%20Palindrome.md)  

[0205. Isomorphic Strings](/Data%20Structure%20and%20Algorithms/LeetCode/0205.%20Isomorphic%20Strings.md)  

[0242. Valid Anagram](/Data%20Structure%20and%20Algorithms/LeetCode/0242.%20Valid%20Anagram.md)  

[0290. Word Pattern](/Data%20Structure%20and%20Algorithms/LeetCode/0290.%20Word%20Pattern.md)  

[0344. Reverse String](/Data%20Structure%20and%20Algorithms/LeetCode/0344.%20Reverse%20String.md)  

[0392. Is Subsequence](/Data%20Structure%20and%20Algorithms/LeetCode/0392.%20Is%20Subsequence.md)  

[0929. Unique Email Addresses](/Data%20Structure%20and%20Algorithms/LeetCode/0929.%20Unique%20Email%20Addresses.md)  

[1209. Remove All Adjacent Duplicates in String II](/Data%20Structure%20and%20Algorithms/LeetCode/1209.%20Remove%20All%20Adjacent%20Duplicates%20in%20String%20II.md)  

[Add Strings](/Data%20Structure%20and%20Algorithms/LeetCode/Add%20Strings.md)  

[Anagram Difference](/Data%20Structure%20and%20Algorithms/LeetCode/Anagram%20Difference.md)  

[Count Binary Substrings](/Data%20Structure%20and%20Algorithms/LeetCode/Count%20Binary%20Substrings.md)  

[Decode String](/Data%20Structure%20and%20Algorithms/LeetCode/Decode%20String.md)  

[Expressive Words](/Data%20Structure%20and%20Algorithms/LeetCode/Expressive%20Words.md)  

[Fraction to Recurring Decimal](/Data%20Structure%20and%20Algorithms/LeetCode/Fraction%20to%20Recurring%20Decimal.md)  

[Minimum Number of Steps to Make Two Strings Anagram](/Data%20Structure%20and%20Algorithms/LeetCode/Minimum%20Number%20of%20Steps%20to%20Make%20Two%20Strings%20Anagram.md)  

[Reorganize String](/Data%20Structure%20and%20Algorithms/LeetCode/Reorganize%20String.md)  

[Reverse Words in a String III](/Data%20Structure%20and%20Algorithms/LeetCode/Reverse%20Words%20in%20a%20String%20III.md)  

[Verifying an Alien Dictionary](/Data%20Structure%20and%20Algorithms/LeetCode/Verifying%20an%20Alien%20Dictionary.md)  

[Word Break](/Data%20Structure%20and%20Algorithms/LeetCode/Word%20Break.md)  

### 🔗 Linked List

[0002. Add Two Numbers](/Data%20Structure%20and%20Algorithms/LeetCode/0002.%20Add%20Two%20Numbers.md)  

[0019. Remove Nth Node From End of List](/Data%20Structure%20and%20Algorithms/LeetCode/0019.%20Remove%20Nth%20Node%20From%20End%20of%20List.md)  

[0021. Merge Two Sorted Lists](/Data%20Structure%20and%20Algorithms/LeetCode/0021.%20Merge%20Two%20Sorted%20Lists.md)  

[0024. Swap Nodes in Pairs](/Data%20Structure%20and%20Algorithms/LeetCode/0024.%20Swap%20Nodes%20in%20Pairs.md)  

[0025. Reverse Nodes in K-Group.md](/Data%20Structure%20and%20Algorithms/LeetCode/0025.%20Reverse%20Nodes%20in%20k-Group.md)

[0061. Rotate List](/Data%20Structure%20and%20Algorithms/LeetCode/0061.%20Rotate%20List.md)  

[0083. Remove Duplicates from Sorted List](/Data%20Structure%20and%20Algorithms/LeetCode/0083.%20Remove%20Duplicates%20from%20Sorted%20List.md)  

[0092. Reverse Linked List II](/Data%20Structure%20and%20Algorithms/LeetCode/0092.%20Reverse%20Linked%20List%20II.md)  

[0143. Reorder List](/Data%20Structure%20and%20Algorithms/LeetCode/0143.%20Reorder%20List.md)  

[0160. Intersection of Two Linked Lists](/Data%20Structure%20and%20Algorithms/LeetCode/0160.%20Intersection%20of%20Two%20Linked%20Lists.md)  

[0203. Remove Linked List Elements](/Data%20Structure%20and%20Algorithms/LeetCode/0203.%20Remove%20Linked%20List%20Elements.md)  

[0206. Reverse Linked List](/Data%20Structure%20and%20Algorithms/LeetCode/0206.%20Reverse%20Linked%20List.md)  

[0234. Palindrome Linked List](/Data%20Structure%20and%20Algorithms/LeetCode/0234.%20Palindrome%20Linked%20List.md)  

[0876. Middle of the Linked List](/Data%20Structure%20and%20Algorithms/LeetCode/0876.%20Middle%20of%20the%20Linked%20List.md)  

[Linked List Cycle](/Data%20Structure%20and%20Algorithms/LeetCode/Linked%20List%20Cycle.md)  

[Linked List Cycle II](/Data%20Structure%20and%20Algorithms/LeetCode/Linked%20List%20Cycle%20II.md)  

### 🌳 Tree

[0094. Binary Tree Inorder Traversal](/Data%20Structure%20and%20Algorithms/LeetCode/0094.%20Binary%20Tree%20Inorder%20Traversal.md)  

[0098. Validate Binary Search Tree](/Data%20Structure%20and%20Algorithms/LeetCode/0098.%20Validate%20Binary%20Search%20Tree.md)  

[0100. Same Tree](/Data%20Structure%20and%20Algorithms/LeetCode/0100.%20Same%20Tree.md)  

[0101. Symmetric Tree](/Data%20Structure%20and%20Algorithms/LeetCode/0101.%20Symmetric%20Tree.md)  

[0102. Binary Tree Level Order Traversal](/Data%20Structure%20and%20Algorithms/LeetCode/0102.%20Binary%20Tree%20Level%20Order%20Traversal.md)  

[0103. Binary Tree Zigzag Level Order Traversal](/Data%20Structure%20and%20Algorithms/LeetCode/0103.%20Binary%20Tree%20Zigzag%20Level%20Order%20Traversal.md)  

[0104. Maximum Depth of Binary Tree](/Data%20Structure%20and%20Algorithms/LeetCode/0104.%20Maximum%20Depth%20of%20Binary%20Tree.md)  

[0105. Construct Binary Tree from Preorder and Inorder Traversal](/Data%20Structure%20and%20Algorithms/LeetCode/0105.%20Construct%20Binary%20Tree%20from%20Preorder%20and%20Inorder%20Traversal.md)  

[0106. Construct Binary Tree from Inorder and Postorder Traversal](/Data%20Structure%20and%20Algorithms/LeetCode/0106.%20Construct%20Binary%20Tree%20from%20Inorder%20and%20Postorder%20Traversal.md)  

[0108. Convert Sorted Array to Binary Search Tree](/Data%20Structure%20and%20Algorithms/LeetCode/0108.%20Convert%20Sorted%20Array%20to%20Binary%20Search%20Tree.md)  

[0110. Balanced Binary Tree](/Data%20Structure%20and%20Algorithms/LeetCode/0110.%20Balanced%20Binary%20Tree.md)  

[0112. Path Sum](/Data%20Structure%20and%20Algorithms/LeetCode/0112.%20Path%20Sum.md)  

[0113. Path Sum II](/Data%20Structure%20and%20Algorithms/LeetCode/0113.%20Path%20Sum%20II.md)  

[0114. Flatten Binary Tree to Linked List](/Data%20Structure%20and%20Algorithms/LeetCode/0114.%20Flatten%20Binary%20Tree%20to%20Linked%20List.md)  

[0117. Populating Next Right Pointers](/Data%20Structure%20and%20Algorithms/LeetCode/0117.%20Populating%20Next%20Right%20Pointers.md)  

[0199. Binary Tree Right Side View](/Data%20Structure%20and%20Algorithms/LeetCode/0199.%20Binary%20Tree%20Right%20Side%20View.md)  

[0226. Invert Binary Tree](/Data%20Structure%20and%20Algorithms/LeetCode/0226.%20Invert%20Binary%20Tree.md)  

[0230. Kth Smallest Element in a BST](/Data%20Structure%20and%20Algorithms/LeetCode/0230.%20Kth%20Smallest%20Element%20in%20a%20BST.md)  

[0236. Lowest Common Ancestor of a Binary Tree](/Data%20Structure%20and%20Algorithms/LeetCode/0236.%20Lowest%20Common%20Ancestor%20of%20a%20Binary%20Tree.md)  

[0285. Inorder Successor in BST](/Data%20Structure%20and%20Algorithms/LeetCode/0285.%20Inorder%20Successor%20in%20BST.md)  

[0297. Serialize and Deserialize Binary Tree](/Data%20Structure%20and%20Algorithms/LeetCode/0297.%20Serialize%20and%20Deserialize%20Binary%20Tree.md)  

[0298. Binary Tree Longest Consecutive Sequence](/Data%20Structure%20and%20Algorithms/LeetCode/0298.%20Binary%20Tree%20Longest%20Consecutive%20Sequence.md)  

[0314. Binary Tree Vertical Order Traversal](/Data%20Structure%20and%20Algorithms/LeetCode/0314.%20Binary%20Tree%20Vertical%20Order%20Traversal.md)  

[0426. Convert Binary Search Tree to Sorted Doubly Linked List](/Data%20Structure%20and%20Algorithms/LeetCode/0426.%20Convert%20Binary%20Search%20Tree%20to%20Sorted%20Doubly%20Linked%20List.md)  

[0510. Inorder Successor in BST II](/Data%20Structure%20and%20Algorithms/LeetCode/0510.%20Inorder%20Successor%20in%20BST%20II.md)  

[0530. Minimum Absolute Difference in BST](/Data%20Structure%20and%20Algorithms/LeetCode/0530.%20Minimum%20Absolute%20Difference%20in%20BST.md)  

[0543. Diameter of Binary Tree](/Data%20Structure%20and%20Algorithms/LeetCode/0543.%20Diameter%20of%20Binary%20Tree.md)  

[0637. Average of Levels in Binary Tree](/Data%20Structure%20and%20Algorithms/LeetCode/0637.%20Average%20of%20Levels%20in%20Binary%20Tree.md)  

[1530. Number of Good Leaf Nodes Pairs](/Data%20Structure%20and%20Algorithms/LeetCode/1530.%20Number%20of%20Good%20Leaf%20Nodes%20Pairs.md)  

[1650. Lowest Common Ancestor of a Binary Tree III](/Data%20Structure%20and%20Algorithms/LeetCode/1650.%20Lowest%20Common%20Ancestor%20of%20a%20Binary%20Tree%20III.md)  

[Lowest Common Ancestor of a Binary Tree](/Data%20Structure%20and%20Algorithms/LeetCode/Lowest%20Common%20Ancestor%20of%20a%20Binary%20Tree.md)  

[Merge Two Binary Trees](/Data%20Structure%20and%20Algorithms/LeetCode/Merge%20Two%20Binary%20Trees.md)  

[Recover Binary Search Tree](/Data%20Structure%20and%20Algorithms/LeetCode/Recover%20Binary%20Search%20Tree.md)  

[Sum Root to Leaf Numbers](/Data%20Structure%20and%20Algorithms/LeetCode/Sum%20Root%20to%20Leaf%20Numbers.md)  

### 🔄 Backtracking

[0017. Letter Combinations of a Phone Number](/Data%20Structure%20and%20Algorithms/LeetCode/0017.%20Letter%20Combinations%20of%20a%20Phone%20Number.md)  

[0022. Generate Parentheses](/Data%20Structure%20and%20Algorithms/LeetCode/0022.%20Generate%20Parentheses.md)  

[0036. Valid Sudoku](/Data%20Structure%20and%20Algorithms/LeetCode/0036.%20Valid%20Sudoku.md)  

[0039. Combination Sum](/Data%20Structure%20and%20Algorithms/LeetCode/0039.%20Combination%20Sum.md)  

[0040. Combination Sum II](/Data%20Structure%20and%20Algorithms/LeetCode/0040.%20Combination%20Sum%20II.md)  

[0046. Permutations](/Data%20Structure%20and%20Algorithms/LeetCode/0046.%20Permutations.md)  

[0047. Permutations II](/Data%20Structure%20and%20Algorithms/LeetCode/0047.%20Permutations%20II.md)  

[0077. Combinations](/Data%20Structure%20and%20Algorithms/LeetCode/0077.%20Combinations.md)  

[0079. Word Search](/Data%20Structure%20and%20Algorithms/LeetCode/0079.%20Word%20Search.md)  

[0212. Word Search II](/Data%20Structure%20and%20Algorithms/LeetCode/0212.%20Word%20Search%20II.md)  

[Combinations](/Data%20Structure%20and%20Algorithms/LeetCode/Combinations.md)  

### 🌐 Graphs, BFS & DFS

[0133. Clone Graph](/Data%20Structure%20and%20Algorithms/LeetCode/0133.%20Clone%20Graph.md)  

[0200. Number of Islands](/Data%20Structure%20and%20Algorithms/LeetCode/0200.%20Number%20of%20Islands.md)  

[0207. Course Schedule](/Data%20Structure%20and%20Algorithms/LeetCode/0207.%20Course%20Schedule.md)  

[0261. Graph Valid Tree](/Data%20Structure%20and%20Algorithms/LeetCode/0261.%20Graph%20Valid%20Tree.md)  

[0329. Longest Increasing Path in a Matrix](/Data%20Structure%20and%20Algorithms/LeetCode/0329.%20Longest%20Increasing%20Path%20in%20a%20Matrix.md)  

[0399. Evaluate Division](/Data%20Structure%20and%20Algorithms/LeetCode/0399.%20Evaluate%20Division.md)  

[0433. Minimum Genetic Mutation](/Data%20Structure%20and%20Algorithms/LeetCode/0433.%20Minimum%20Genetic%20Mutation.md)  

[0694. Number of Distinct Islands](/Data%20Structure%20and%20Algorithms/LeetCode/0694.%20Number%20of%20Distinct%20Islands.md)  

[0909. Snakes and Ladders](/Data%20Structure%20and%20Algorithms/LeetCode/0909.%20Snakes%20and%20Ladders.md)  

[1091. Shortest Path in Binary Matrix](/Data%20Structure%20and%20Algorithms/LeetCode/1091.%20Shortest%20Path%20in%20Binary%20Matrix.md)  

[Flood Fill](/Data%20Structure%20and%20Algorithms/LeetCode/Flood%20Fill.md)  

[Max Area of Island](/Data%20Structure%20and%20Algorithms/LeetCode/Max%20Area%20of%20Island.md)  

[Minimum Knight Moves](/Data%20Structure%20and%20Algorithms/LeetCode/Minimum%20Knight%20Moves.md)  

[Rotting Oranges](/Data%20Structure%20and%20Algorithms/LeetCode/Rotting%20Oranges.md)  

### 🔍 Binary Search & Search

[0033. Search in Rotated Sorted Array](/Data%20Structure%20and%20Algorithms/LeetCode/0033.%20Search%20in%20Rotated%20Sorted%20Array.md)  

[0034. Find First and Last Position of Element in Sorted Array](/Data%20Structure%20and%20Algorithms/LeetCode/0034.%20Find%20First%20and%20Last%20Position%20of%20Element%20in%20Sorted%20Array.md)  

[0035. Search Insert Position](/Data%20Structure%20and%20Algorithms/LeetCode/0035.%20Search%20Insert%20Position.md)  

[0127. Word Ladder](/Data%20Structure%20and%20Algorithms/LeetCode/0127.%20Word%20Ladder.md)  

[0374. Guess Number Higher or Lower](/Data%20Structure%20and%20Algorithms/LeetCode/0374.%20Guess%20Number%20Higher%20or%20Lower.md)  

[1268. Search Suggestions System](/Data%20Structure%20and%20Algorithms/LeetCode/1268.%20Search%20Suggestions%20System.md)  

[Binary Search](/Data%20Structure%20and%20Algorithms/LeetCode/Binary%20Search.md)  

[Find Peak Element](/Data%20Structure%20and%20Algorithms/LeetCode/Find%20Peak%20Element.md)  

[First Bad Version](/Data%20Structure%20and%20Algorithms/LeetCode/First%20Bad%20Version.md)  

### 📈 Dynamic Programming

[0045. Jump Game II](/Data%20Structure%20and%20Algorithms/LeetCode/0045.%20Jump%20Game%20II.md)  

[0055. Jump Game](/Data%20Structure%20and%20Algorithms/LeetCode/0055.%20Jump%20Game.md)  

[0062. Unique Paths](/Data%20Structure%20and%20Algorithms/LeetCode/0062.%20Unique%20Paths.md)  

[0118. Pascal's Triangle](/Data%20Structure%20and%20Algorithms/LeetCode/0118.%20Pascal's%20Triangle.md)  

[0119. Pascal's Triangle II](/Data%20Structure%20and%20Algorithms/LeetCode/0119.%20Pascal's%20Triangle%20II.md)  

[0121. Best Time to Buy and Sell Stock](/Data%20Structure%20and%20Algorithms/LeetCode/0121.%20Best%20Time%20to%20Buy%20and%20Sell%20Stock.md)  

[0122. Best Time to Buy and Sell Stock II](/Data%20Structure%20and%20Algorithms/LeetCode/0122.%20Best%20Time%20to%20Buy%20and%20Sell%20Stock%20II.md)  

[0130. Surrounded Regions](/Data%20Structure%20and%20Algorithms/LeetCode/0130.%20Surrounded%20Regions.md)  

[1048. Longest String Chain](/Data%20Structure%20and%20Algorithms/LeetCode/1048.%20Longest%20String%20Chain.md)  

[1930. Unique Length-3 Palindromic Subsequences](/Data%20Structure%20and%20Algorithms/LeetCode/1930.%20Unique%20Length-3%20Palindromic%20Subsequences.md)  

[Maximum Subarray](/Data%20Structure%20and%20Algorithms/LeetCode/Maximum%20Subarray.md)  

[Minimum Moves to Equal Array Elements](/Data%20Structure%20and%20Algorithms/LeetCode/Minimum%20Moves%20to%20Equal%20Array%20Elements.md)  

[Minimum Size Subarray Sum](/Data%20Structure%20and%20Algorithms/LeetCode/Minimum%20Size%20Subarray%20Sum.md)  

### #️⃣ Hash Map & Set

[0049. Group Anagrams](/Data%20Structure%20and%20Algorithms/LeetCode/0049.%20Group%20Anagrams.md)  

[0128. Longest Consecutive Sequence](/Data%20Structure%20and%20Algorithms/LeetCode/0128.%20Longest%20Consecutive%20Sequence.md)  

[0136. Single Number](/Data%20Structure%20and%20Algorithms/LeetCode/0136.%20Single%20Number.md)  

[0169. Majority Element](/Data%20Structure%20and%20Algorithms/LeetCode/0169.%20Majority%20Element.md)  

[0217. Contains Duplicate](/Data%20Structure%20and%20Algorithms/LeetCode/0217.%20Contains%20Duplicate.md)  

[0219. Contains Duplicate II](/Data%20Structure%20and%20Algorithms/LeetCode/0219.%20Contains%20Duplicate%20II.md)  

[0243. Shortest Word Distance](/Data%20Structure%20and%20Algorithms/LeetCode/0243.%20Shortest%20Word%20Distance.md)  

[0268. Missing Number](/Data%20Structure%20and%20Algorithms/LeetCode/0268.%20Missing%20Number.md)  

[0448. Find All Numbers Disappeared in an Array](/Data%20Structure%20and%20Algorithms/LeetCode/0448.%20Find%20All%20Numbers%20Disappeared%20in%20an%20Array.md)  

[0496. Next Greater Element I](/Data%20Structure%20and%20Algorithms/LeetCode/0496.%20Next%20Greater%20Element%20I.md)  

[0560. Subarray Sum Equals K](/Data%20Structure%20and%20Algorithms/LeetCode/0560.%20Subarray%20Sum%20Equals%20K.md)  

[1189. Maximum Number of Balloons](/Data%20Structure%20and%20Algorithms/LeetCode/1189.%20Maximum%20Number%20of%20Balloons.md)  

[1207. Unique Number of Occurrences](/Data%20Structure%20and%20Algorithms/LeetCode/1207.%20Unique%20Number%20of%20Occurrences.md)  

[Count Duplicate Elements](/Data%20Structure%20and%20Algorithms/LeetCode/Count%20Duplicate%20Elements.md)  

[Minimum Deletions to Make Character Frequencies Unique](/Data%20Structure%20and%20Algorithms/LeetCode/Minimum%20Deletions%20to%20Make%20Character%20Frequencies%20Unique.md)  

[Subdomain Visit Count](/Data%20Structure%20and%20Algorithms/LeetCode/Subdomain%20Visit%20Count.md)  

### 🔢 Math & Number Theory

[0007. Reverse Integer](/Data%20Structure%20and%20Algorithms/LeetCode/0007.%20Reverse%20Integer.md)  

[0009. Palindrome Number](/Data%20Structure%20and%20Algorithms/LeetCode/0009.%20Palindrome%20Number.md)  

[0050. Pow(x, n)](/Data%20Structure%20and%20Algorithms/LeetCode/0050.%20Pow(x,%20n).md)  

[0163. Missing Ranges](/Data%20Structure%20and%20Algorithms/LeetCode/0163.%20Missing%20Ranges.md)  

[0228. Summary Ranges](/Data%20Structure%20and%20Algorithms/LeetCode/0228.%20Summary%20Ranges.md)  

[0367. Valid Perfect Square](/Data%20Structure%20and%20Algorithms/LeetCode/0367.%20Valid%20Perfect%20Square.md)  

[0441. Arranging Coins](/Data%20Structure%20and%20Algorithms/LeetCode/0441.%20Arranging%20Coins.md)  

[0682. Baseball Game](/Data%20Structure%20and%20Algorithms/LeetCode/0682.%20Baseball%20Game.md)  

[0923. 3Sum With Multiplicity](/Data%20Structure%20and%20Algorithms/LeetCode/0923.%20_3Sum%20With%20Multiplicity.md)  

[Sum of Square Numbers](/Data%20Structure%20and%20Algorithms/LeetCode/Sum%20of%20Square%20Numbers.md)  

### 🧩 Matrix

[0048. Rotate Image](/Data%20Structure%20and%20Algorithms/LeetCode/0048.%20Rotate%20Image.md)  

[0054. Spiral Matrix](/Data%20Structure%20and%20Algorithms/LeetCode/0054.%20Spiral%20Matrix.md)  

[0059. Spiral Matrix II](/Data%20Structure%20and%20Algorithms/LeetCode/0059.%20Spiral%20Matrix%20II.md)  

[0329. Longest Increasing Path in a Matrix](/Data%20Structure%20and%20Algorithms/LeetCode/0329.%20Longest%20Increasing%20Path%20in%20a%20Matrix.md)  

[0542. 01 Matrix](/Data%20Structure%20and%20Algorithms/LeetCode/0542.%2001%20Matrix.md)  

[0554. Brick Wall](/Data%20Structure%20and%20Algorithms/LeetCode/0554.%20Brick%20Wall.md)  

[2133. Check if Every Row and Column Contains All Numbers](/Data%20Structure%20and%20Algorithms/LeetCode/2133.%20Check%20if%20Every%20Row%20and%20Column%20Contains%20All%20Numbers.md)  

[Search a 2D Matrix II](/Data%20Structure%20and%20Algorithms/LeetCode/Search%20a%202D%20Matrix%20II.md)  

### 🎯 Design & Data Structure

[0146. LRU Cache](/Data%20Structure%20and%20Algorithms/LeetCode/0146.%20LRU%20Cache.md)  

[0225. Implement Stack using Queues](/Data%20Structure%20and%20Algorithms/LeetCode/0225.%20Implement%20Stack%20using%20Queues.md)  

[0252. Meeting Rooms](/Data%20Structure%20and%20Algorithms/LeetCode/0252.%20Meeting%20Rooms.md)  

[0380. Insert Delete GetRandom O(1)](/Data%20Structure%20and%20Algorithms/LeetCode/0380.%20Insert%20Delete%20GetRandom%20O(1).md)  

[0353. SnakeGame](/Data%20Structure%20and%20Algorithms/LeetCode/0353%20SnakeGame.md)  

[Accounts Merge](/Data%20Structure%20and%20Algorithms/LeetCode/Accounts%20Merge.md)  

[Design Linked List](/Data%20Structure%20and%20Algorithms/LeetCode/Design%20Linked%20List.md)  

[Find Duplicate File in System](/Data%20Structure%20and%20Algorithms/LeetCode/Find%20Duplicate%20File%20in%20System.md)  

[Kth Largest Element in an Array](/Data%20Structure%20and%20Algorithms/LeetCode/Kth%20Largest%20Element%20in%20an%20Array.md)  

[Meeting Rooms II](/Data%20Structure%20and%20Algorithms/LeetCode/Meeting%20Rooms%20II.md)  

[Time Based Key-Value Store](/Data%20Structure%20and%20Algorithms/LeetCode/Time%20Based%20Key-Value%20Store.md)  

[Top K Frequent Words](/Data%20Structure%20and%20Algorithms/LeetCode/Top%20K%20Frequent%20Words.md)  

### 🌱 Beginners

Beginner Algorithm Problems

[0001. Sum of positive](/Data%20Structure%20and%20Algorithms/Beginners/0001.%20Sum%20of%20positive.md)  

[0002. Return Negative](/Data%20Structure%20and%20Algorithms/Beginners/0002.%20Return%20Negative.md)  

[0003. Opposite number](/Data%20Structure%20and%20Algorithms/Beginners/0003.%20Opposite%20number.md)  

[0004. Remove First and Last Character](/Data%20Structure%20and%20Algorithms/Beginners/0004.%20Remove%20First%20and%20Last%20Character.md)  

[0005. Reversed String](/Data%20Structure%20and%20Algorithms/Beginners/0005.%20Reversed%20String.md)  

[0006. String repeat](/Data%20Structure%20and%20Algorithms/Beginners/0006.%20String%20repeat.md)  

[0026. Replace Character](/Data%20Structure%20and%20Algorithms/Beginners/0026.%20Replace%20Character.md)  

[0027. Consecutive Duplicates with Count](/Data%20Structure%20and%20Algorithms/Beginners/0027.%20Consecutive%20Duplicates%20with%20Count.md)  

[0028. toCamelCase](/Data%20Structure%20and%20Algorithms/Beginners/0028.%20toCamelCase.md)  

[0029. Dig pow](/Data%20Structure%20and%20Algorithms/Beginners/0029.%20Dig%20pow.md)  

[0030. Equal Sides Of An Array](/Data%20Structure%20and%20Algorithms/Beginners/0030.%20Equal%20Sides%20Of%20An%20Array.md)  

[0031. Match Strings](/Data%20Structure%20and%20Algorithms/Beginners/0031.%20Match%20Strings.md)  

[07. Find the smallest integer in the array](/Data%20Structure%20and%20Algorithms/Beginners/07.%20Find%20the%20smallest%20integer%20in%20the%20array.md)  

[08. Square Every Digit](/Data%20Structure%20and%20Algorithms/Beginners/08.%20%20Square%20Every%20Digit.md)  

[09. Remove all vowels from string](/Data%20Structure%20and%20Algorithms/Beginners/09.%20Remove%20all%20vowels%20from%20string.md)  

[10. Highest and Lowest](/Data%20Structure%20and%20Algorithms/Beginners/10.%20Highest%20and%20Lowest.md)  

[11. Descending Order](/Data%20Structure%20and%20Algorithms/Beginners/11.%20Descending%20Order.md)  

[12. Mumbling](/Data%20Structure%20and%20Algorithms/Beginners/12.%20Mumbling.md)  

[13. Get the middle string](/Data%20Structure%20and%20Algorithms/Beginners/13.%20Get%20the%20middle%20string.md)  

[14. Check if a number is square](/Data%20Structure%20and%20Algorithms/Beginners/14.%20Check%20if%20a%20number%20is%20square.md)  

[15. Isograms](/Data%20Structure%20and%20Algorithms/Beginners/15.%20Isograms.md)  

[16. Exes and Ohs](/Data%20Structure%20and%20Algorithms/Beginners/16.%20Exes%20and%20Ohs.md)  

[17. Jaden Casing Strings](/Data%20Structure%20and%20Algorithms/Beginners/17.%20Jaden%20Casing%20Strings.md)  

[18. Length of the shortest word in a string](/Data%20Structure%20and%20Algorithms/Beginners/18.%20Length%20of%20the%20shortest%20word%20in%20a%20string.md)  

[19. Reverse a string from a given index](/Data%20Structure%20and%20Algorithms/Beginners/19.%20Reverse%20a%20string%20from%20a%20given%20index.md)  

[20. Credit card mask](/Data%20Structure%20and%20Algorithms/Beginners/20.%20Credit%20card%20mask.md)  

[21. Two to one](/Data%20Structure%20and%20Algorithms/Beginners/21.%20Two%20to%20one.md)  

[22. Categorize New Member](/Data%20Structure%20and%20Algorithms/Beginners/22.%20Categorize%20New%20Member.md)  

[23. Find the odd int](/Data%20Structure%20and%20Algorithms/Beginners/23.%20Find%20the%20odd%20int.md)  

[24. Sum of Digits](/Data%20Structure%20and%20Algorithms/Beginners/24.%20Sum%20of%20Digits.md)  

[25. Stop gninnipS My sdroW](/Data%20Structure%20and%20Algorithms/Beginners/25.%20Stop%20gninnipS%20My%20sdroW.md)  

---

## 🏗️ System Design

Master system design principles and real-world architecture patterns. Perfect for technical interview preparation and building scalable systems.

### 📚 System Design Course

**Foundations & Interview Preparation**

[001. Introduction to System Design](/System%20Design/System%20Design%20Course/001.%20Introduction/Introduction.md)

#### 002. System Design Interviews

[What is a System Design Interview?](/System%20Design/System%20Design%20Course/002.%20System%20Design%20Interviews/what%20is%20a%20system%20design%20interview.md)  

[How to Prepare for Success](/System%20Design/System%20Design%20Course/002.%20System%20Design%20Interviews/how%20to%20prepare%20for%20success.md)  

[How to Perform Well](/System%20Design/System%20Design%20Course/002.%20System%20Design%20Interviews/how%20to%20preform%20well.md)

### 🌍 System Design in Real World

Practical case studies and real-world system design examples.

[001. Tiny URL](/System%20Design/System%20Design%20in%20Real%20World/001.%20Tiny%20URL.md)  

[002. Design a Parking Lot System](/System%20Design/System%20Design%20in%20Real%20World/002.%20Design%20a%20Parking%20Lot%20System.md)  

[003. Design a Fitness Tracking App](/System%20Design/System%20Design%20in%20Real%20World/003.%20Design%20a%20Fitness%20Tracking%20App.md)  

[004. Design a Weather Reporting System](/System%20Design/System%20Design%20in%20Real%20World/004.%20Design%20a%20Weather%20Reporting%20System.md)  

[005. Design Pastebin](/System%20Design/System%20Design%20in%20Real%20World/005.%20Design%20Pastebin.md)  

[006. Design a Nested Comments System](/System%20Design/System%20Design%20in%20Real%20World/006.Design%20a%20Nested%20Comments%20System.md)  

[007. Design an Online Presence Indicator Service](/System%20Design/System%20Design%20in%20Real%20World/007.Design%20an%20Online%20Presence%20Indicator%20Service.md)

---

## 🚀 Modern C++ Notes

Comprehensive C++ tutorials and notes covering modern C++ features and best practices.

[001. The main function](/Modern%20C%2B%2B%20Notes/001.%20The%20main%20function/The%20main%20Function.md)  

[002. Constants in C++](/Modern%20C%2B%2B%20Notes/002.%20Constants%20in%20C%2B%2B/Constants%20in%20C%2B%2B.md)  

[003. Variables in C++](/Modern%20C%2B%2B%20Notes/003.%20Variables%20in%20C%2B%2B/Tutotial.md)

---

## 📖 Web Development Basics

Essential concepts for web development interviews and mastering web fundamentals.

[1. What happens when you type in a URL](https://github.com/cheatsheet1999/FrontEndCollection/issues/2)  

[2. GET vs POST](https://github.com/cheatsheet1999/FrontEndCollection/issues/4)  

[3. What can we do to improve a website's performance?](https://github.com/cheatsheet1999/FrontEndCollection/issues/5)  

[4. HTML5 offline storage mechanism](https://github.com/cheatsheet1999/FrontEndCollection/issues/6)  

[5. Common time and space-complexity](https://github.com/cheatsheet1999/FrontEndCollection/issues/9)  

[6. What has been deprecated, and what is new on HTML5?](https://github.com/cheatsheet1999/FrontEndCollection/issues/11)  

[7. How the DOM really works?](https://github.com/cheatsheet1999/FrontEndCollection/issues/18)  

[8. Inline elements, Block elements, and what are the differences?](https://github.com/cheatsheet1999/FrontEndCollection/issues/27)  

[9. Several ways to call a function](https://github.com/cheatsheet1999/FrontEndCollection/issues/28)  

[10. A brief introduction of the differences between "src" and "href"](https://github.com/cheatsheet1999/FrontEndCollection/issues/29)  

[11. A brief introduction of Call, Apply, Bind](https://github.com/cheatsheet1999/FrontEndCollection/issues/30)  

[12. Time and space complexity for common sorting algorithm](https://github.com/cheatsheet1999/FrontEndCollection/issues/9)  

[13. What is the difference between display:none and visibility:hidden style?](https://github.com/cheatsheet1999/FrontEndCollection/issues/37)  

[14. What is BFC(Block Formatting Context)](https://github.com/cheatsheet1999/FrontEndCollection/issues/38)

### 📦 JavaScript Concepts  

[1. `this` keyword](https://github.com/cheatsheet1999/FrontEndCollection/blob/main/Web-Note/%60this%60%20keyword.md)   

[2. Bubbling and Capturing](https://github.com/cheatsheet1999/FrontEndCollection/blob/main/Web-Note/Bubbling%20and%20Capturing.md)   

[3. Execution Context](https://github.com/cheatsheet1999/FrontEndCollection/blob/main/Web-Note/Execution%20Context.md)   

[4. Higher Order Function](https://github.com/cheatsheet1999/FrontEndCollection/blob/main/Web-Note/Functions%20%26%20Callbacks.md)      

[5. Event Loop](https://github.com/cheatsheet1999/FrontEndCollection/blob/main/Web-Note/Single%20Thread,%20Event%20Loop%20&%20Blocking%20Code.md)      

[6. Closures](https://github.com/cheatsheet1999/FrontEndCollection/blob/main/Web-Note/Closures.md)   

[7. Throttling and Debouncing](https://github.com/cheatsheet1999/FrontEndCollection/blob/main/Web-Note/Throttling%20and%20Debouncing.md)   

[8. Promises](https://github.com/cheatsheet1999/FrontEndCollection/blob/main/Web-Note/Promises.md) 

[9. Consuming Promises](https://github.com/cheatsheet1999/FrontEndCollection/tree/main/JS-Day/Consuming%20Promises)      

[10. Controlled Components](https://github.com/cheatsheet1999/FrontEndCollection/tree/main/Web-Note/Controlled%20Components)   

[11. ExpenseTracker](https://github.com/cheatsheet1999/FrontEndCollection/tree/main/React/ExpenseTracker)    

[12. Receive input](https://github.com/cheatsheet1999/FrontEndCollection/blob/main/JS-Day/Receive%20input/preview.md)     

[13. Accordion](https://github.com/cheatsheet1999/FrontEndCollection/issues/17)   

[14. ModalBox](https://github.com/cheatsheet1999/FrontEndCollection/issues/23)  

[15. Drum Kit](https://github.com/cheatsheet1999/FrontEndCollection/tree/main/JS-Day/DrumKit)  

[16. Mini Clock](https://github.com/cheatsheet1999/FrontEndCollection/tree/main/JS-Day/Mini%20Clock)  

[17. Playing with Variables](https://github.com/siyuan25/FrontEndCollection/tree/main/JS-Day/Playing%20with%20Variables)  

### 🔬 Deep Dive in Javascript 

[18. Implement Curry()](https://github.com/cheatsheet1999/FrontEndCollection/issues/33)   

[19. implement Array.prototype.flat()](https://github.com/cheatsheet1999/FrontEndCollection/blob/main/JS-Core/implement%20Array.prototype.flat().md)  

[20. Implement curry() with placeholder support](https://github.com/cheatsheet1999/FrontEndCollection/blob/main/JS-Core/implement%20curry()%20with%20placeholder%20support.md)

---

## 📖 Miscellaneous

### Other Learning Resources

[Distributed Systems Fundamentals - Web Basics](/Distributed%20Systems%20Fundamentals/Web%20Basics)

---

## 🤝 Contributing

If you find errors in the content of this project, don't hesitate to submit issues or pull requests on GitHub for corrections. Contributions are always welcome!

## 📝 License

This project is open source and available for educational purposes.

---
ecosyste.ms

Data

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Indexes

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Experiments

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