This application is a small command line utility used to solve the 8-puzzle game. This implementation uses the A * Search algorithm to find the goal state. The Manhattan distance is used to calculate the heuristic of the puzzle at each state. This project was written for the senior level Artificial Intelligence class at my university. An example of an initial state and goal state of the 8-puzzle game are shown below.

Initial State:

Goal State:

This is a Java project using Maven. The two dependencies you'll need are:

• Java JDK
• Maven

Being by cloning the repository, or downloading the repository as a zip file.

$ git clone https://github.com/caseyscarborough/puzzle.git && cd puzzle

Once you've retrieved the repository and are in the project's directory, you can package the project using Maven and run it manually using the following commands:

$ mvn package -P cli-dist
$ java -cp target/Puzzle.jar com.caseyscarborough.puzzle.Puzzle

If you are on a UNIX-based system, run script/build to package the application using Maven and script/puzzle to run the application:

$ script/build
$ script/puzzle

Note: This may require you to chmod the scripts make them executable: chmod u+x script/*

The application will then block and allow you to input a sliding puzzle in the following format:

0 1 2
4 5 3
7 6 8

Zeros or blank spaces can be used for the input of the application, meaning all of these inputs are valid:

1 5 2        4 1 2          4 3        0 1 2
4 0 3        5 8          1 7 6        4 5 3
7 6 8        7 3 6        8 2 5        7 6 8

You have the option to give two optional parameters. The first is a filename to read from, and the second is a filename to write the output solution to.

Windows:

> java -cp target\Puzzle.jar com.caseyscarborough.puzzle.Puzzle in.txt out.txt

Mac OS X/Linux:

$ script/puzzle in.txt out.txt

The format of the input file should match the same as the input you'd give on the console. This means three lines, with three numbers, each separated by a space. See below:

4 1 2
5 3 6
0 7 8

The following are some sample puzzles to test the application out with.

0 5 2
1 8 3
4 7 6

4 1 2
5 8 3
7 0 6

Note: This one takes a minute!
7 2 3
4 6 5
1 8 0

These are not solvable.
1 2 3
4 5 6
8 7 0

1 5 0
3 2 8
4 6 7