CoinCrawler

CoinCrawler is a deterministic grid‑navigation engine implemented in Scala 3, designed around constrained movement, collision handling, and region‑based coin aggregation. The system models a 10×10 board with walls, coins, and player state, and exposes a minimal API for movement, scoring, and path suggestion under strict structural rules.

Architecture & Framework

Language: Scala Paradigm: Functional / Imperative hybrid Runtime: JVM (Liberica / OpenJDK) Testing: JUnit IDE: IntelliJ IDEA The project intentionally avoids external frameworks to keep the logic transparent, testable, and self‑contained.

Core Mechanics:

Movement

• Commands: w (up), a (left), s (down), d (right)
• Movement is atomic and validated against board boundaries and walls
• Illegal moves are ignored without side effects

Coin Handling

• Positive cell values represent coins
• Entering a coin cell increments the score and clears the cell
• Re‑entry yields no additional points

Save & Region Sweep

• save() stores the current coordinates
• Subsequent movement defines an axis‑aligned rectangle
• When the rectangle covers ≥ 9 cells, all coins inside are collected
• Saved coordinates reset after a sweep

Path Suggestion suggestMove(x, y) returns a deterministic two‑segment path (horizontal→vertical or vertical→horizontal) that:

• Avoids walls
• Respects board boundaries
• Returns an empty string if no valid path exists
• Does not mutate game state

Project Structure

src/

 cw/

  ├── Game.scala            // Core engine
  
  ├── GameBuilder.scala     // Board initialization utilities
  
  └── GameApp.scala         // Entry point

Guidelines for running the Project

• Open the project in IntelliJ with Scala support
• Scala-sdk should be added as a dependency as well.
• Download Junit4 in the library and add in the dependency to run the tests.
• Run GameApp.scala to play the game.

Testing

The engine is validated through unit tests covering:

• Boundary conditions
• Wall collisions
• Coin collection semantics
• Region sweep correctness
• Path suggestion validity
• Board initialization

Purpose of the framework

CoinCrawler serves as a compact demonstration of:

• Grid‑based state management
• Algorithmic reasoning
• Deterministic movement systems
• Test‑driven development in Scala
• Clean, framework‑independent design

Authors

Sanjana Akter Jemi