Data Structures Lab

This repository is a Java practice space for learning data structures in two different ways:

1. use existing data structures well
2. build custom data structures from scratch

That split is the main rule used to organise this project.

Repository split

1. Use existing data structures

Path:

• src/main/java/existing/data/structures/

This side is for Java's built-in and standard-library data structures. It focuses on usage, access patterns, basic API understanding, and practical behaviour.

2. Custom data structures

Path:

• src/main/java/custom/data/structures/

This side is for handwritten implementations. It focuses on internal logic, node/array handling, edge cases, and interview-style practice.

Current folder structure

DataStructuresLab/
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   ├── custom/data/structures/
│   │   │   │   ├── arrays/
│   │   │   │   ├── linkedLists/
│   │   │   │   ├── list/
│   │   │   │   ├── stacks/
│   │   │   │   ├── queues/
│   │   │   │   ├── trees/
│   │   │   │   ├── graphs/
│   │   │   │   ├── hashing/
│   │   │   │   ├── Main.java
│   │   │   │   └── README.md
│   │   │   └── existing/data/structures/
│   │   │       ├── arrays/
│   │   │       ├── lists/
│   │   │       ├── maps/
│   │   │       ├── queuesanddeques/
│   │   │       └── README.md
│   │   └── resources/
│   └── test/
│       └── java/
│           ├── custom/data/structures/
│           └── existing/data/structures/
├── pom.xml
└── README.md

What is implemented right now

Existing data structures track

Implemented:

• ✅ native Java arrays
• ✅ non-primitive static 1D array wrapper
• ✅ non-primitive static 2D array wrapper

Planned but not implemented yet:

• ⬜ Java List usage
• ⬜ Java Map usage
• ⬜ Java queue and deque usage

Main source folder in use:

• src/main/java/existing/data/structures/arrays/

Main test folder in use:

• src/test/java/existing/data/structures/arrays/

Custom data structures track

Implemented:

• ✅ custom dynamic array
• ✅ custom array-backed list
• ✅ singly linked list
• ✅ doubly linked list
• ✅ singly circular linked list
• ✅ doubly circular linked list
• ✅ fixed stack
• ✅ linked-list stack
• ✅ simple queue
• ✅ deque
• ✅ binary tree node structure
• ✅ binary search tree insert
• ✅ binary search tree search
• ✅ binary search tree delete
• ✅ adjacency matrix representation
• ✅ adjacency list representation
• ✅ breadth-first search
• ✅ depth-first search

Planned but not implemented yet:

• ⬜ hashing structures
• ⬜ AVL tree
• ⬜ trie
• ⬜ circular queue / ring buffer
• ⬜ advanced specialised structures

Main source folders in use:

• src/main/java/custom/data/structures/arrays/
• src/main/java/custom/data/structures/list/
• src/main/java/custom/data/structures/linkedLists/
• src/main/java/custom/data/structures/stacks/
• src/main/java/custom/data/structures/queues/
• src/main/java/custom/data/structures/trees/
• src/main/java/custom/data/structures/graphs/

Main test folders in use:

• src/test/java/custom/data/structures/arrays/
• src/test/java/custom/data/structures/list/
• src/test/java/custom/data/structures/linkedLists/
• src/test/java/custom/data/structures/stacks/
• src/test/java/custom/data/structures/queues/
• src/test/java/custom/data/structures/trees/
• src/test/java/custom/data/structures/graphs/

Folder notes

• custom/data/structures/arrays/ now owns the custom dynamic-array implementation.
• existing/data/structures/arrays/ is reserved for Java array usage work.
• custom/data/structures/linkedLists/ contains all linked-list implementations currently in the project.
• existing/data/structures/queuesanddeques/ uses a valid folder name without hyphens.
• hashing/, lists/, maps/, and queuesanddeques/ are still mostly planning folders at the moment.

Test coverage notes

This repository now has test classes for:

• existing arrays
• custom dynamic arrays
• custom linked lists
• custom list
• custom stacks
• custom queues
• custom trees
• custom graphs

Surefire test reports are generated under:

• target/surefire-reports/

Build and run

The packaged entry point used by the project is:

• custom.data.structures.Main

Common Maven commands:

mvn clean package
mvn test
mvn spring-boot:run

Run folder-specific demo classes directly from the IDE if needed:

• custom.data.structures.arrays.Main
• custom.data.structures.list.Main
• custom.data.structures.linkedLists.LinkedListsMain
• custom.data.structures.stacks.Main
• custom.data.structures.queues.Main
• custom.data.structures.graphs.Main
• custom.data.structures.trees.Main
• existing.data.structures.arrays.ArraysMain

Why this repository is organised this way

This project is meant to stay clean and long-term maintainable.

The goal is to keep a clear difference between:

• using Java's existing data structures properly
• understanding how those structures work by implementing them yourself

That makes the repository useful for revision, interview preparation, and step-by-step practice.