DSA-Java

A personal, real-time learning log of Data Structures & Algorithms implemented in Java — including LeetCode problem solutions, notes, and small experiments.
Repo: iamtahasc/DSA-Java

This repository is how I learn and practice DSA — I solve problems, write clean Java implementations, add short notes about approach and complexity, and update the repo as I make progress. Everything here is a work in progress and reflects my current learning journey.

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What this repo is for (my goals)

• Learn and implement core data structures (arrays, linked lists, stacks, queues, trees, graphs, heaps, tries, hash maps).
• Practice problem solving with LeetCode-style problems and similar interview questions.
• Track progress in real time — each commit represents something I learned or fixed.
• Keep solutions readable, documented, and reusable.

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How I use this repo (real-time workflow)

1. Pick a problem (LeetCode, interview question, or a concept to implement).
2. Create a new Java file in the appropriate folder (e.g., arrays/, trees/, dynamic-programming/).
3. Add a short header comment: problem name/link, difficulty, date, time & space complexity.
4. Add unit tests or a main demo if helpful.
5. Commit with a clear message like: feat: add LeetCode 2 Add Two Numbers (linkedlist) — 2025-06-01.
6. If it's a harder topic, add notes (approach, edge-cases) in the same file or in notes/.
7. Open an issue if I want to revisit an optimization later or track follow-ups.

Example daily routine:

• Solve 1–3 problems a day (read, plan, implement, test).
• Push solutions and short notes.
• Update progress tracker (see "Progress" below).

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Repository layout (convention)

• /arrays
• /linkedlists
• /stacks-queues
• /trees
• /graphs
• /dynamic-programming
• /sorting
• /math
• /utils
• /notes — short writeups, complexity analyses, and todo items
• README.md (you are here)

File naming convention:

• LeetCode solutions: LeetCode{ID}_{ProblemName}.java
  Example: LeetCode2_AddTwoNumbers.java
• Self-contained structure implementations: LinkedList_Singly.java, Trie.java
• Tests (if present): tests/ or src/test/java/

Top of each Java file (recommended header):

/**
 * Problem: Add Two Numbers
 * Source: LeetCode 2 (https://leetcode.com/problems/add-two-numbers/)
 * Difficulty: Medium
 * Date: 2025-06-01
 * Time: O(max(n, m))
 * Space: O(max(n, m))
 */

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How to compile & run (quick)

If files are plain Java with packages:

• Compile a single file: javac -d out src/your/package/LeetCode2_AddTwoNumbers.java

• Compile whole project (simple): find . -name "*.java" > sources.txt javac -d out @sources.txt

• Run a class with main: java -cp out your.package.LeetCode2_AddTwoNumbers

(If you add Maven/Gradle later, update this README with commands like mvn test or ./gradlew run.)

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Progress tracking (real-time)

I keep progress visible so I can see how I'm improving:

• Commit history — each solved problem is a small milestone.
• Issues — I create issues for topics to study more or refactors I want to do.
• Optional: If I add a PROGRESS.md or GitHub Project board, I track weekly goals and solved counts.

Suggested short progress table (can put in PROGRESS.md):

Date	Problem (link)	Difficulty	Notes / Status
2025-06-01	LeetCode 2 — Add Two Numbers	Medium	Implemented; needs edge-case tests
2025-06-02	Binary Tree Inorder Traversal	Easy	Done; iterative and recursive

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Learning notes & best practices I follow

• Write a short plan before coding (approach & complexity).
• Start with a correct, readable solution. Optimize only when necessary.
• Add tests for edge cases (empty inputs, single node, duplicates).
• Keep code modular and small. Extract helper methods when needed.
• When stuck, write pseudo-code or draw the structure.

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Contributing / Collaborating

This is primarily my learning repo, but contributions and suggestions are welcome.

If you want to contribute:

1. Fork the repo.
2. Create a branch: feat/<topic>-<short-desc>
3. Add your solution and tests.
4. Follow naming and header conventions.
5. Open a PR with a clear description.

Please be respectful — explain design choices and include complexity notes.

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Roadmap / TODO

• Add JUnit tests and a simple build (pom.xml or build.gradle).
• Add PROGRESS.md that automatically lists solved problems (manual for now).
• Implement more graph algorithms and dynamic programming examples.
• Add example interview-style README with common patterns and tips.

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License & Contact

• This repo is my personal study project.
• Maintainer: iamtahasc — https://github.com/iamtahasc