🧠 COMP251 – Data Structures & Algorithms (UFV)

Author: Michael Buss
Course: UFV COMP 251 – Data Structures & Algorithms
Purpose: A clean, working Java portfolio demonstrating foundational data structure implementations from the course — refactored for readability, modularity, and real-world GitHub presentation.

“The best way to understand data structures is to build them from scratch.”
— The CompSci RV Dad 🚐💻

---

🧩 Contents

• Stack – Push/pop operations, string reversal, balanced parentheses, infix→postfix conversion.
• Queue – FIFO structures, enqueue/dequeue, and circular queue simulation.
• Linked List – Node-based design with insert, delete, and concatenation methods.
• Trees – Binary tree creation, recursive traversals (preorder, inorder, postorder).
• Recursion – Factorial, Fibonacci, and sum-of-odds recursive examples.

---

🧱 Project Overview

This repository showcases reusable, well-structured implementations of core data structures written in Java — each organized under its own package:

Package	Description
Stack/	Abstract List Interface (ADTList) and ArrayBasedList implementation for array-based storage and dynamic resizing.
LinkedList/	Full suite of linked list types including Node<T>, SinglyLinkedList<T>, DLLNode, and DoublyLinkedList.
Trees/	Basic BinaryTree and TestBinaryTree implementation with traversal examples.
Recursion/	Reserved for future algorithm and recursion exercises.
Queue/	Reserved for upcoming queue and circular buffer examples.

---

🧩 Example Run – Singly Linked List

SinglyLinkedList<String> list = new SinglyLinkedList<>();
list.add("Alpha");
list.add("Bravo");
list.add("Charlie");

System.out.println("Initial List: " + list);
list.remove(1);
System.out.println("After Removal: " + list);
System.out.println("Element at Index 1: " + list.get(1));
System.out.println("Is Empty? " + list.isEmpty());
System.out.println("Size: " + list.size());

---

Output:

Initial List: [Alpha, Bravo, Charlie] After Removal: [Alpha, Charlie] Element at Index 1: Charlie Is Empty? false Size: 2

---

🧩 Example Run – Doubly Linked List

DoublyLinkedList<String> list = new DoublyLinkedList<>();

list.add("Alpha");
list.add("Bravo");
list.add("Charlie");
System.out.println("Initial List (Forward): " + list);

list.add(1, "Delta");
System.out.println("After Insertion at index 1 (Forward): " + list);

System.out.println("Element at index 2: " + list.get(2));

list.remove(1);
System.out.println("After Removal at index 1 (Forward): " + list);

System.out.println("Backward Traversal: " + list.toReverseString());

System.out.println("Is Empty? " + list.isEmpty());
System.out.println("Size: " + list.size());

---

Output:

Initial List (Forward): [Alpha, Bravo, Charlie]
After Insertion at index 1 (Forward): [Alpha, Delta, Bravo, Charlie]
Element at index 2: Bravo
After Removal at index 1 (Forward): [Alpha, Bravo, Charlie]
Backward Traversal: [Charlie, Bravo, Alpha]
Is Empty? false
Size: 3

---

## 🧩 Example Run – Array-Based List

```java
ArrayBasedList<String> list = new ArrayBasedList<>(10);
list.add("Alpha");
list.add("Bravo");
list.add("Charlie");
System.out.println("Initial List: " + list);

list.add(1, "Delta");
System.out.println("After Insertion at index 1: " + list);

System.out.println("Element at index 2: " + list.get(2));

list.remove(1);
System.out.println("After Removal at index 1: " + list);

System.out.println("Is Empty? " + list.isEmpty());
System.out.println("Size: " + list.size());

---

Output:

Initial List: [Alpha, Bravo, Charlie], Size: 3, Capacity: 10
After Insertion at index 1: [Alpha, Delta, Bravo, Charlie], Size: 4, Capacity: 10
Element at index 2: Bravo
After Removal at index 1: [Alpha, Bravo, Charlie], Size: 3, Capacity: 10
Is Empty? false
Size: 3

---

## 🌳 Example Run – Binary Tree Traversal

```java
BinaryTree<Integer> tree = new BinaryTree<>();
int[] values = {4, 2, 3, 35, 25, 48, 87, 109, 270};
for (int v : values) tree.insert(v);

System.out.println("Preorder: " + tree.preorder());
System.out.println("Inorder: " + tree.inorder());
System.out.println("Postorder: " + tree.postorder());
System.out.println("Level Order (BFS): " + tree.levelOrder());

---

Output:

Preorder: [4, 2, 35, 25, 48, 87, 3, 109, 270]
Inorder: [35, 2, 48, 25, 87, 4, 109, 3, 270]
Postorder: [35, 48, 87, 25, 2, 109, 270, 3, 4]
Level Order (BFS): [4, 2, 3, 35, 25, 109, 270, 48, 87]

---

## 🧠 Learning Goals
- Strengthen understanding of Big-O analysis and algorithmic efficiency.  
- Practice recursion and iterative design.  
- Reinforce OOP concepts using generics in Java.  
- Develop clean, modular, and reusable code.

---

⚙️ Tech Notes
Language: Java 17+
IDE/Editor: Visual Studio Code & Terminal
Structure: Multi-package organization under /src and /out
Compilation:

javac -d out src/Stack/*.java src/LinkedList/*.java
java -cp out LinkedList.TestSinglyList

---

## 🛠️ Tools
- **Language:** Java 17  
- **IDE:** VS Code  
- **Version Control:** Git + GitHub

---

🧭 Learning Reflection
This project was part of my hands-on journey through UFV’s COMP 251 course.
It helped me strengthen my understanding of:
Java package and classpath management
Generic data type design (Node<T>, ADTList<T>)
Algorithmic thinking through linked data structures
Building, testing, and debugging modular Java projects
Using Git for version control and portfolio presentation

---

🚀 Next Steps
Implement Queue and Recursion examples
Extend Tree package with traversal visualization
Add JUnit tests for automated validation
Document each data structure’s time complexity

---

👨‍💻 Maintained by Michael Buss — aka The CompSci RV Dad 🚐☕


---


> *“The best way to understand data structures is to build them from scratch.”*

## 📂 Folder Overview
- `src/Stack/` → push/pop, balanced parentheses, infix→postfix  
- `src/Queue/` → enqueue/dequeue, circular queue  
- `src/LinkedList/` → singly linked lists, concatenation  
- `src/Trees/` → binary tree insert/traversals  
- `src/Recursion/` → factorial, Fibonacci, sum odds