Notes for Software Engineers on infrastructure and distributed systems. Covers common data structure and algorithms, web concepts, and more!
CloudCollection ๐
A comprehensive collection of algorithm solutions, system design materials, and modern C++ tutorials. Perfect for interview preparation, learning, and reference.
๐งฎ Data Structures & Algorithms
Organized by topic and difficulty level, with detailed solutions and explanations.
๐ Array & Two Pointers
0001. Two Sum 0011. Container With Most Water 0015. 3Sum 0016. 3Sum Closest 0018. 4Sum 0027. Remove Element 0031. Next Permutation 0042. Trapping Rain Water 0045. Jump Game II 0055. Jump Game 0056. Merge Intervals 0057. Insert Interval 0066. Plus One 0075. Sort Colors 0088. Merge Sorted Array 0189. Rotate Array 0238. Product of Array Except Self 0283. Move Zeroes 0347. Top K Frequent Elements 0349. Intersection of Two Arrays 0350. Intersection of Two Arrays II 0605. Can Place Flowers 0724. Find Pivot Index 1010. Pairs of Songs With Total Durations Divisible by 60 1299. Replace Elements with Greatest Element on Right Side 1984. Minimum Difference Between Highest and Lowest of K Scores Two Sum II - Input Array Is Sorted
๐ String
0003. Longest Substring Without Repeating Characters 0005. Longest Palindromic Substring 0006. Zigzag Conversion 0012. Integer to Roman 0013. Roman to Integer 0014. Longest Common Prefix 0020. Valid Parentheses 0028. Find the Index of the First Occurrence in a String 0038. Count and Say 0043. Multiply Strings 0058. Length of Last Word 0071. Simplify Path 0125. Valid Palindrome 0205. Isomorphic Strings 0242. Valid Anagram 0290. Word Pattern 0344. Reverse String 0392. Is Subsequence 0929. Unique Email Addresses 1209. Remove All Adjacent Duplicates in String II Add Strings Anagram Difference Count Binary Substrings Decode String Expressive Words Fraction to Recurring Decimal Minimum Number of Steps to Make Two Strings Anagram Reorganize String Reverse Words in a String III Verifying an Alien Dictionary Word Break
๐ Linked List
0002. Add Two Numbers 0019. Remove Nth Node From End of List 0021. Merge Two Sorted Lists 0024. Swap Nodes in Pairs 0025. Reverse Nodes in K-Group.md 0061. Rotate List 0083. Remove Duplicates from Sorted List 0092. Reverse Linked List II 0143. Reorder List 0160. Intersection of Two Linked Lists 0203. Remove Linked List Elements 0206. Reverse Linked List 0234. Palindrome Linked List 0876. Middle of the Linked List Linked List Cycle Linked List Cycle II
๐ณ Tree
0094. Binary Tree Inorder Traversal 0098. Validate Binary Search Tree 0100. Same Tree 0101. Symmetric Tree 0102. Binary Tree Level Order Traversal 0103. Binary Tree Zigzag Level Order Traversal 0104. Maximum Depth of Binary Tree 0105. Construct Binary Tree from Preorder and Inorder Traversal 0106. Construct Binary Tree from Inorder and Postorder Traversal 0108. Convert Sorted Array to Binary Search Tree 0110. Balanced Binary Tree 0112. Path Sum 0113. Path Sum II 0114. Flatten Binary Tree to Linked List 0117. Populating Next Right Pointers 0199. Binary Tree Right Side View 0226. Invert Binary Tree 0230. Kth Smallest Element in a BST 0236. Lowest Common Ancestor of a Binary Tree 0285. Inorder Successor in BST 0297. Serialize and Deserialize Binary Tree 0298. Binary Tree Longest Consecutive Sequence 0314. Binary Tree Vertical Order Traversal 0426. Convert Binary Search Tree to Sorted Doubly Linked List 0510. Inorder Successor in BST II 0530. Minimum Absolute Difference in BST 0543. Diameter of Binary Tree 0637. Average of Levels in Binary Tree 1530. Number of Good Leaf Nodes Pairs 1650. Lowest Common Ancestor of a Binary Tree III Lowest Common Ancestor of a Binary Tree Merge Two Binary Trees Recover Binary Search Tree Sum Root to Leaf Numbers
๐ Backtracking
0017. Letter Combinations of a Phone Number 0022. Generate Parentheses 0036. Valid Sudoku 0039. Combination Sum 0040. Combination Sum II 0046. Permutations 0047. Permutations II 0077. Combinations 0079. Word Search 0212. Word Search II Combinations
๐ Graphs, BFS & DFS
0133. Clone Graph 0200. Number of Islands 0207. Course Schedule 0261. Graph Valid Tree 0329. Longest Increasing Path in a Matrix 0399. Evaluate Division 0433. Minimum Genetic Mutation 0694. Number of Distinct Islands 0909. Snakes and Ladders 1091. Shortest Path in Binary Matrix Flood Fill Max Area of Island Minimum Knight Moves Rotting Oranges
๐ Binary Search & Search
0033. Search in Rotated Sorted Array 0034. Find First and Last Position of Element in Sorted Array 0035. Search Insert Position 0127. Word Ladder 0374. Guess Number Higher or Lower 1268. Search Suggestions System Binary Search Find Peak Element First Bad Version
๐ Dynamic Programming
0045. Jump Game II 0055. Jump Game 0062. Unique Paths 0118. Pascal's Triangle 0119. Pascal's Triangle II 0121. Best Time to Buy and Sell Stock 0122. Best Time to Buy and Sell Stock II 0130. Surrounded Regions 1048. Longest String Chain 1930. Unique Length-3 Palindromic Subsequences Maximum Subarray Minimum Moves to Equal Array Elements Minimum Size Subarray Sum
#๏ธโฃ Hash Map & Set
0049. Group Anagrams 0128. Longest Consecutive Sequence 0136. Single Number 0169. Majority Element 0217. Contains Duplicate 0219. Contains Duplicate II 0243. Shortest Word Distance 0268. Missing Number 0448. Find All Numbers Disappeared in an Array 0496. Next Greater Element I 0560. Subarray Sum Equals K 1189. Maximum Number of Balloons 1207. Unique Number of Occurrences Count Duplicate Elements Minimum Deletions to Make Character Frequencies Unique Subdomain Visit Count
๐ข Math & Number Theory
0007. Reverse Integer 0009. Palindrome Number 0050. Pow(x, n).md) 0163. Missing Ranges 0228. Summary Ranges 0367. Valid Perfect Square 0441. Arranging Coins 0682. Baseball Game 0923. 3Sum With Multiplicity Sum of Square Numbers
๐งฉ Matrix
0048. Rotate Image 0054. Spiral Matrix 0059. Spiral Matrix II 0329. Longest Increasing Path in a Matrix 0542. 01 Matrix 0554. Brick Wall 2133. Check if Every Row and Column Contains All Numbers Search a 2D Matrix II
๐ฏ Design & Data Structure
0146. LRU Cache 0225. Implement Stack using Queues 0252. Meeting Rooms 0380. Insert Delete GetRandom O(1).md) 0353. SnakeGame Accounts Merge Design Linked List Find Duplicate File in System Kth Largest Element in an Array Meeting Rooms II Time Based Key-Value Store Top K Frequent Words
๐ฑ Beginners
Beginner Algorithm Problems
0001. Sum of positive 0002. Return Negative 0003. Opposite number 0004. Remove First and Last Character 0005. Reversed String 0006. String repeat 0026. Replace Character 0027. Consecutive Duplicates with Count 0028. toCamelCase 0029. Dig pow 0030. Equal Sides Of An Array 0031. Match Strings 07. Find the smallest integer in the array 08. Square Every Digit 09. Remove all vowels from string 10. Highest and Lowest 11. Descending Order 12. Mumbling 13. Get the middle string 14. Check if a number is square 15. Isograms 16. Exes and Ohs 17. Jaden Casing Strings 18. Length of the shortest word in a string 19. Reverse a string from a given index 20. Credit card mask 21. Two to one 22. Categorize New Member 23. Find the odd int 24. Sum of Digits 25. Stop gninnipS My sdroW
๐๏ธ System Design
Master system design principles and real-world architecture patterns. Perfect for technical interview preparation and building scalable systems.
๐ System Design Course
Foundations & Interview Preparation
001. Introduction to System Design
002. System Design Interviews
What is a System Design Interview? How to Prepare for Success How to Perform Well
๐ System Design in Real World
Practical case studies and real-world system design examples.
001. Tiny URL 002. Design a Parking Lot System 003. Design a Fitness Tracking App 004. Design a Weather Reporting System 005. Design Pastebin 006. Design a Nested Comments System 007. Design an Online Presence Indicator Service
๐ Modern C++ Notes
Comprehensive C++ tutorials and notes covering modern C++ features and best practices.
001. The main function 002. Constants in C++ 003. Variables in C++
๐ Web Development Basics
Essential concepts for web development interviews and mastering web fundamentals.
1. What happens when you type in a URL 2. GET vs POST 3. What can we do to improve a website's performance? 4. HTML5 offline storage mechanism 5. Common time and space-complexity 6. What has been deprecated, and what is new on HTML5? 7. How the DOM really works? 8. Inline elements, Block elements, and what are the differences? 9. Several ways to call a function 10. A brief introduction of the differences between "src" and "href" 11. A brief introduction of Call, Apply, Bind 12. Time and space complexity for common sorting algorithm 13. What is the difference between display:none and visibility:hidden style? 14. What is BFC(Block Formatting Context)
๐ฆ JavaScript Concepts
1. this keyword 2. Bubbling and Capturing 3. Execution Context 4. Higher Order Function 5. Event Loop 6. Closures 7. Throttling and Debouncing 8. Promises 9. Consuming Promises 10. Controlled Components 11. ExpenseTracker 12. Receive input 13. Accordion 14. ModalBox 15. Drum Kit 16. Mini Clock 17. Playing with Variables
๐ฌ Deep Dive in Javascript
18. Implement Curry() 19. implement Array.prototype.flat().md) 20. Implement curry() with placeholder support%20with%20placeholder%20support.md)
๐ Miscellaneous
Other Learning Resources
Distributed Systems Fundamentals - Web Basics
๐ค 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!
๐ License
This project is open source and available for educational purposes.
