Data Structures and Algorithms

A comprehensive guide to mastering Data Structures and Algorithms (DSA) using Java. This repository includes in-depth explanations, coding exercises, and interview preparation tools to help you solve complex problems and excel in technical interviews. Perfect for beginners and advanced learners alike!

Overview

This repo covers fundamental concepts, data structures, and algorithms to solve coding problems effectively, with a focus on interview preparation. Each module includes key problems, concepts, and bonus challenges.

Table of Contents

Module	Topics Covered	Key Problems	Quizzes/Bonus
1. Introduction	Big O notation, recursion	Recursive problem solving	Quiz
2. Arrays and Strings	Arrays, Strings, two pointers, sliding window, prefix sum	Reverse String, Squares of a Sorted Array, Maximum Average Subarray I, K Radius Subarray Averages	Arrays & Strings Quiz, Bonus Problems
3. Hashing	Hashing fundamentals, counting elements, checking existence	Pangram Sentence, Missing Number, Ransom Note, Longest Substring Without Repeating Characters	Hashing Quiz, Bonus Problems
4. Linked Lists	Fast & slow pointers, linked list operations, reversing linked lists	Middle of Linked List, Remove Duplicates, Reverse Linked List II	Linked Lists Quiz, Bonus Problems
5. Stacks and Queues	Stack & queue operations, string problems, monotonic stack	Simplify Path, Moving Average, Online Stock Span, Make The String Great	Stacks & Queues Quiz, Bonus Problems
6. Trees and Graphs	Binary trees (DFS, BFS), binary search trees, graphs (DFS, BFS), implicit graphs	Min Depth of Binary Tree, Closest BST Value, Max Area of Island, Word Ladder, Find Path in Graph	Trees & Graphs Quiz, Bonus Problems
7. Heaps	Heap operations, priority queues, top k problems	Kth Largest Element in Array, K Closest Points, Min Cost to Connect Sticks	Heaps Quiz, Bonus Problems
8. Greedy Algorithms	Greedy strategies, maximizing & minimizing problems	Maximum 69 Number, Max Units on a Truck, Reduce Array Size to Half	Greedy Quiz, Bonus Problems
9. Binary Search	Binary search on arrays, search in solution spaces	Search Insert Position, Find Smallest Divisor, Split Array Largest Sum	Binary Search Quiz, Bonus Problems
10. Backtracking	Backtracking generation, combinations, permutations	Generate Parentheses, Letter Combinations, Combination Sum III	Backtracking Quiz, Bonus Problems
11. Dynamic Programming	1D DP, multidimensional DP, matrix DP	Climbing Stairs, Coin Change, Unique Paths II, Best Time to Buy and Sell Stock	Dynamic Programming Quiz, Bonus Problems
12. Bonus Topics	Difference arrays, tries, bit manipulation, Dijkstra’s Algorithm, modular arithmetic	Hamming Distance, Cheapest Flights Within K Stops, Implement Trie, Insert Interval	Final Quiz, Bonus Problems

Getting Started

Prerequisites

• Basic understanding of programming language (Java)
• Familiarity with coding environments like Eclipse, VS Code, IntelliJ, or others

How to Use

1. Clone the repository:

   git clone https://github.com/psrsekhar/learn-dsa-with-java.git

2. Navigate through the course modules in each folder.

Project Structure

Quizzes

Each module contains quizzes to test your understanding of the concepts. You can find the quizzes in the quizzes/ folder for each module.

• Module 1 Quiz: module1-quiz.md
• Module 2 Quiz: module2-quiz.md
• Module 3 Quiz: module3-quiz.md
• Module 4 Quiz: module4-quiz.md
• Module 5 Quiz: module5-quiz.md
• Module 6 Quiz: module6-quiz.md
• Module 7 Quiz: module7-quiz.md
• Module 8 Quiz: module8-quiz.md
• Module 9 Quiz: module9-quiz.md
• Module 10 Quiz: module10-quiz.md
• Module 11 Quiz: module11-quiz.md
• Module 12 Quiz: module12-quiz.md

Resources

• resources/Cheatsheets.md - Helpful algorithm and data structure cheatsheets
• resources/Visualizations/ - Folder for visual aids or diagrams (if any)

Folder Structure

learn-dsa-with-java/
│
├── README.md                     # Main repository overview
├── .gitignore                    # Git ignore file for Java projects
├── LICENSE                       # License file (e.g., MIT License)
├── quizzes/                      # Folder for quizzes across all modules
│   ├── module01-quiz.md
│   ├── module02-quiz.md
│   ├── module03-quiz.md
│   ├── module04-quiz.md
│   ├── module05-quiz.md
│   ├── module06-quiz.md
│   ├── module07-quiz.md
│   ├── module08-quiz.md
│   ├── module09-quiz.md
│   ├── module10-quiz.md
│   ├── module11-quiz.md
│   ├── module12-quiz.md
│
├── modules/introduction/          # Folder for Module 1: Introduction
│   ├── README.md                 # Module 1 overview and learning materials
│   ├── BigONotation.java         # Java implementation for Big O problems
│   ├── RecursionExamples.java    # Java implementation for recursion problems
│
├── modules/arrays-and-strings/    # Folder for Module 2: Arrays and Strings
│   ├── README.md                 # Module 2 overview and learning materials
│   ├── ReverseString.java        # Java implementation for reverse string
│   ├── SlidingWindow.java        # Java implementation for sliding window problems
│   ├── PrefixSum.java            # Java implementation for prefix sum problems
│
├── modules/hashing/               # Folder for Module 3: Hashing
│   ├── README.md                 # Module 3 overview and learning materials
│   ├── PangramChecker.java       # Java implementation for pangram problem
│   ├── LongestSubstring.java     # Java implementation for longest substring without repeating characters
│
├── modules/linked-lists/          # Folder for Module 4: Linked Lists
│   ├── README.md                 # Module 4 overview and learning materials
│   ├── LinkedListOperations.java # Java implementation for common linked list operations
│   ├── ReverseLinkedList.java    # Java implementation for reversing a linked list
│
├── modules/stacks-and-queues/     # Folder for Module 5: Stacks and Queues
│   ├── README.md                 # Module 5 overview and learning materials
│   ├── StackOperations.java      # Java implementation for stack-based problems
│   ├── QueueOperations.java      # Java implementation for queue-based problems
│   ├── MonotonicStack.java       # Java implementation for monotonic stack problems
│
├── modules/trees-and-graphs/      # Folder for Module 6: Trees and Graphs
│   ├── README.md                 # Module 6 overview and learning materials
│   ├── BinaryTreeDFS.java        # Java implementation for binary tree DFS traversal
│   ├── GraphBFS.java             # Java implementation for graph BFS traversal
│   ├── BinarySearchTree.java     # Java implementation for binary search trees
│
├── modules/heaps/                # Folder for Module 7: Heaps
│   ├── README.md                 # Module 7 overview and learning materials
│   ├── HeapOperations.java       # Java implementation for heap operations
│   ├── KthLargestElement.java     # Java implementation for Kth Largest Element in an Array
│   ├── KClosestPoints.java        # Java implementation for K Closest Points to Origin
│   └── MinCostToConnectSticks.java # Java implementation for Min Cost to Connect Sticks
│
├── modules/greedy-algorithms/    # Folder for Module 8: Greedy Algorithms
│   ├── README.md                 # Module 8 overview and learning materials
│   ├── Maximum69Number.java      # Java implementation for Maximum 69 Number
│   ├── MaxUnitsOnTruck.java      # Java implementation for Max Units on a Truck
│   └── ReduceArraySize.java      # Java implementation for Reduce Array Size to Half
│
├── modules/binary-search/        # Folder for Module 9: Binary Search
│   ├── README.md                 # Module 9 overview and learning materials
│   ├── SearchInsertPosition.java  # Java implementation for Search Insert Position
│   ├── FindSmallestDivisor.java   # Java implementation for Find Smallest Divisor Given a Threshold
│   └── SplitArrayLargestSum.java  # Java implementation for Split Array Largest Sum
│
├── modules/backtracking/        # Folder for Module 10: Backtracking
│   ├── README.md                 # Module 10 overview and learning materials
│   ├── GenerateParentheses.java   # Java implementation for Generate Parentheses
│   ├── LetterCombinations.java    # Java implementation for Letter Combinations of a Phone Number
│   └── CombinationSumIII.java     # Java implementation for Combination Sum III
│
├── modules/dynamic-programming/  # Folder for Module 11: Dynamic Programming
│   ├── README.md                 # Module 11 overview and learning materials
│   ├── ClimbingStairs.java        # Java implementation for Climbing Stairs
│   ├── CoinChange.java            # Java implementation for Coin Change
│   ├── UniquePathsII.java         # Java implementation for Unique Paths II
│   └── BestTimeToBuyAndSellStock.java # Java implementation for Best Time to Buy and Sell Stock
│
├── modules/bonus-topics/        # Folder for Module 12: Bonus Topics
│   ├── README.md                 # Module 12 overview and learning materials
│   ├── HammingDistance.java       # Java implementation for Hamming Distance
│   ├── CheapestFlightsWithinKStops.java # Java implementation for Cheapest Flights Within K Stops
│   ├── ImplementTrie.java         # Java implementation for Implementing a Trie (Prefix Tree)
│   └── InsertInterval.java        # Java implementation for Insert Interval
│
├── tests/                        # Folder for unit tests
│   ├── ArrayTests.java           # JUnit tests for array-based algorithms
│   ├── HashingTests.java         # JUnit tests for hashing problems
│   ├── LinkedListTests.java      # JUnit tests for linked list operations
│   ├── TreeTests.java            # JUnit tests for tree-based algorithms
│   ├── HeapTests.java            # JUnit tests for heap operations
│   ├── GreedyTests.java          # JUnit tests for greedy algorithms
│   ├── BinarySearchTests.java     # JUnit tests for binary search algorithms
│   ├── BacktrackingTests.java      # JUnit tests for backtracking algorithms
│   ├── DynamicProgrammingTests.java # JUnit tests for dynamic programming algorithms
│   └── BonusTopicsTests.java      # JUnit tests for bonus topics
└── resources/                    # Folder for extra materials (cheatsheets, diagrams, etc.)
    ├── Cheatsheets.md            # Helpful algorithm and data structure cheatsheets
    ├── Visualizations/           # Folder for visual aids or diagrams (if any)

Contribution

Feel free to contribute by submitting pull requests for any improvements, adding new problems, or fixing errors in the content. Happy Learning! 🎉