Java DSA Journey 🚀

A structured Data Structures & Algorithms repository built using Java, focused on mastering coding interviews through Pattern-Based Learning.

This repository documents my journey of learning DSA, solving problems systematically, understanding underlying patterns, and building strong problem-solving skills for Software Development Engineer (SDE) roles.

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🎯 Goals

• Master Data Structures & Algorithms in Java
• Develop strong problem-solving skills
• Learn common coding interview patterns
• Write clean and optimized solutions
• Prepare for Software Engineering interviews
• Track progress throughout my DSA journey

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🧠 Learning Approach

Instead of only organizing problems by difficulty, this repository follows a Pattern-Based Learning approach.

Every problem is categorized by:

1. Data Structure / Topic
2. Problem-Solving Pattern

Examples

Problem	Topic	Pattern
Two Sum II	Arrays	Two Pointers
Container With Most Water	Arrays	Two Pointers
Longest Substring Without Repeating Characters	Strings	Sliding Window
Linked List Cycle	Linked List	Fast & Slow Pointers
Reverse Linked List	Linked List	Reversal
Subarray Sum Equals K	Arrays	Prefix Sum

This helps build pattern recognition, which is one of the most important skills in technical interviews.

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🗂️ Repository Structure

src/
├── a_Foundations
│
├── b_Sorting
│
├── c_Arrays
│   ├── a_Traversal
│   ├── b_TwoPointers
│   ├── c_SlidingWindow
│   ├── d_PrefixSum
│   ├── e_KadaneAlgorithm
│   └── f_Matrix
│
├── d_Strings
│   ├── a_TwoPointers
│   └── b_SlidingWindow
│
└── e_LinkedList
    ├── SinglyLinkedList
    │   ├── a_BasicOperations
    │   ├── b_FastSlowPointers
    │   ├── c_Reversal
    │   ├── d_TwoPointers
    │   ├── e_DummyNode
    │   ├── f_MergeOrSort
    │   └── g_HashMapOrStack
    │
    └── DoublyLinkedList
        ├── a_BasicOperations
        └── b_Reversal

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🧩 Problem-Solving Patterns

This repository focuses heavily on interview patterns such as:

• Two Pointers
• Sliding Window
• Fast & Slow Pointers
• Prefix Sum
• Kadane's Algorithm
• Reversal Pattern
• Dummy Node Pattern
• Merge / Sort Pattern
• HashMap Pattern
• Stack-Based Pattern

Each pattern folder contains:

• Pattern Notes
• Recognition Clues
• Generic Templates
• Practice Problems
• Java Implementations

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📈 Current Progress

Topic	Status
Foundations	✅
Sorting	✅
Arrays	🚧
Strings	🚧
Linked Lists	🚧
Recursion	⏳
Binary Search	⏳
Stack	⏳
Queue	⏳
Trees	⏳
Graphs	⏳
Dynamic Programming	⏳

Legend

• ✅ Completed
• 🚧 In Progress
• ⏳ Planned

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🔍 Problem Solving Workflow

For every problem:

1. Understand the problem statement
2. Identify the underlying pattern
3. Build a brute-force solution
4. Optimize the approach
5. Analyze Time Complexity
6. Analyze Space Complexity
7. Implement clean Java code

Whenever applicable, solutions include:

• Brute Force Approach
• Better Approach
• Optimal Approach

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⚡ Tech Stack

• Java
• IntelliJ IDEA
• Git
• GitHub

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🎓 Current Focus

Actively preparing for:

• Software Development Engineer (SDE) Roles
• Coding Interviews
• Technical Assessments
• Campus Placements

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🤝 Contributions

This repository is maintained primarily for learning and interview preparation.

Suggestions, optimizations, and improvements are always welcome.

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⭐ Connect With Me

GitHub

https://github.com/prakashsalapu

LinkedIn

https://linkedin.com/in/prakashsalapu

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If you find this repository useful, consider giving it a ⭐

It motivates me to continue documenting and improving my DSA journey.