A Star Puzzle Solver

View an example of use here

A TypeScript lib that solves Puzzle Game problem using the A* Algorithm

Installation

Use the package manager npm to install A* Puzzle Solver.

npm install a-star-puzzle-solver

How to use

ES6

import AStarPuzzleSolver from 'a-star-puzzle-solver';

const solution = AStarPuzzleSolver.solvePuzzle(state);

CommonJS

const AStar = require('a-star-puzzle-solver').default;

AStar.solvePuzzle(state);

UMD in Browser

<!-- to import non-minified version -->
<script src="a-star-puzzle-solver.umd.js"></script>

<!-- to import minified version -->
<script src="a-star-puzzle-solver.umd.min.js"></script>

After that the library will be available to the Global as AStarPuzzleSolver. Follow an example:

const aStar = AStarPuzzleSolver;

const solution = aStar.solvePuzzle(state);

Methods

Follow the methods this library provides:

solvePuzzle(initialState)

Solves the 8 Puzzle Game with provided initial state.

Arguments

Argument	Type	Options
initialState	Array of Numbers	Any state possible

Example

const state = [1, 2, 3, 4, 5, 6, 7, 0, 8];

const solution = AStar.solvePuzzle(state);
/*
Obs:
- Pay atention to the order of elements 
- Internally, this state is interpreted like this:
    [
    [1, 2, 3],
    [4, 5, 6],
    [7, 0, 8]
    ]
*/

Return

This method return an object containing:

• pathCost: Total cost of the algorithm (also known as depth of final state)
• expandedNodes: quantity of nodes visited by the algorithm from the initial state to the final state
• iterations: quantity of interation loops inside the algorithm until arrive final state
• solution: an array of objects (each object has the following properties):
  • state: an array with same format the one provided initially
  • operation: a String that represents the operation applied to achieve the state.
    • possible values:
      • 'UP_OPERATION'
      • 'RIGHT_OPERATION'
      • 'DOWN_OPERATION'
      • 'LEFT_OPERATION'
      • 'NONE'
• finalNode: an object wich you can use to access all solution
  • properties:
    • operation: a String that represents the operation applied to achieve the state (values are same indicated above).
    • evaluationFunctionValue: an object that represents value of
      • properties:
        • g: depth of node
        • h: heuristic value
        • f: sum of 'g' and 'h'
    • state: state of node, but in a different format of states provided by solution's array (see convertStateInArray method below)
    • previousNode: another object with same properties (represents parent node of this one)

Obs:

• For more examples of how to use, see './examples' folder
• The goalState considered by the algorithm is:

convertStateInArray(state)

Receives a multidimensional array (3x3) and return an unidimensional (with 9 positions).

Arguments

Argument	Type	Options
state	Multidimensional array of Numbers	Any state possible

Example

const state = [[1, 2, 3], [4, 5, 6], [7, 0, 8]];

const arr = AStar.convertStateInArray(state);

Return

This method return an unidimensional array similar to this:

//Considering argument of example above
[1, 2, 3, 4, 5, 6, 7, 0, 8]

convertArrayInState(arr)

Does the exact opposite of convertStateInArray. Receives an unidimensional array of 9 positions and return multidimensional one (3x3).

Arguments

Argument	Type	Options
arr	Unidimensional array of Numbers	Any state possible

Example

const arr = [1, 2, 3, 4, 5, 6, 7, 0, 8];

const state = AStar.convertArrayInState(arr);

Return

This method return a multidimensional array similar to this:

//Considering argument of example above
[[1, 2, 3], [4, 5, 6], [7, 0, 8]]

isSolvable(state)

Receives a state and returns whether it is solvable or not.

Arguments

Argument	Type	Options
state	Multidimensional array of Numbers	Any state possible

Example

const state = [[1, 2, 3], [4, 5, 6], [7, 0, 8]];

const isSolvable: boolean = AStar.isSolvable(state);

Return

This method return a boolean value indicating whether state is solvable or not:

true | false

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

License

This project is licensed under the MIT License - see the LICENSE.md file for details