/**

* Finds and return a solution to the problem, consisting of a list of

* states.

*

* The list should start with the initial state of the underlying problem.

* Then, it should have one or more additional states. Each state should be

* a successor of its predecessor. The last state should be a goal state of

* the underlying problem.

*

* If there is no solution, then this method should return an empty list.

*

* @return a solution to the problem (or an empty list)

*/

public List findSolution() {

// TODO

return null;

}

This is for an 8-puzzle game. It is supposed to find the solution to the problem.