AStar-Labyrinth

Interactive web visualization of A* pathfinding on randomized labyrinths.

The project is built with React for UI rendering, while all algorithmic logic is implemented in plain JavaScript modules.

Project Objective

Find the shortest path between a start cell and a goal cell in a randomized maze using A*:

• Evaluation function: f(n) = g(n) + h(n)
• Heuristic: Manhattan distance

Syllabus Integration

Topic 3: Binary Trees (Open List)

The frontier (open list) is implemented as a Binary Min-Heap:

• peek for best candidate access
• popMin and pushOrUpdate in O(log n)
• supports frequent priority updates during exploration

File: src/logic/structures/BinaryMinHeap.js

Topic 2: Red-Black Trees (Closed List)

Visited nodes (closed list) are stored in a Red-Black Tree:

• guaranteed self-balancing behavior
• membership checks in O(log n)
• avoids degeneration for adversarial insertion orders

File: src/logic/structures/RedBlackTree.js

A* Engine

Core search logic:

• expands lowest f(n) node first
• tracks cameFrom and gScore
• reconstructs final shortest path
• emits step events for live visualization

File: src/logic/pathfinding/aStar.js

Visualization

The React interface shows:

• randomized maze generation (20x20, 30x30, 50x50)
• frontier expansion (open and closed states)
• current processed node
• final traced shortest path

Main UI files:

• src/App.jsx
• src/components/Grid.jsx
• src/components/Controls.jsx
• src/components/Legend.jsx

Performance Notes

By combining A* with tree-based structures:

• open-list priority operations stay efficient under heavy updates
• closed-list membership remains logarithmic even on long corridors
• larger labyrinths (30x30, 50x50) remain responsive in-browser

Run Locally

npm install
npm run dev

Open the URL shown by Vite (usually http://localhost:5173).

Validation

npm run lint
npm run test
npm run build

Tests

Unit tests are included for:

• Binary Min-Heap behavior
• Red-Black Tree insertion/membership behavior
• A* shortest-path correctness and no-path scenarios

Test files:

• src/logic/structures/BinaryMinHeap.test.js
• src/logic/structures/RedBlackTree.test.js
• src/logic/pathfinding/aStar.test.js