/*
The method solve searches for a solution.
The Printwriter argument is used to specify where the output should be directed.
NOTE: The editing was done in the GameState class. I changed it to allow me to pass
back an array of gamestates that were in the correct format and they had already
been formatted to remove illegal moves.
*/
public void solve(
PrintWriter
output) { // takes the output format as an arguement, so that it can be output to the
// textfile.
unexpanded.add(rootNode); // adds the current rootnode Node object to the unexpanded arraylist.
while (unexpanded.size()
> 0) { // loop whilst the arraylist holding the unexpanded nodes is populated
Node n =
unexpanded.get(0); // Node object n equals the first member of the unexpanded arraylist
expanded.add(n); // adds the node n to the exppanded arraylist
unexpanded.remove(
0); // removes the current node n, which is also the first object,from the unexpanded
// arraylist
if (n.state.isGoal()) { // if the node n matches the goal state, (if the boards are the same)
reportSolution(
n,
output); // the solution is reported using the reportsolution method where the node and
// output are supplied
return; // breaks the while loop as the solution has been found
} else { // otherwise
ArrayList<GameState> moveList =
n.state
.possibleMoves(); // move list array initiated and populated with the possible moves
// from state n
for (GameState gs :
moveList) { // for each state in possible moves, use the temporary GameState var gs
if ((Node.findNodeWithState(unexpanded, gs) == null)
&& // if the current gamestate is not in the unexpanded arraylist and...
(Node.findNodeWithState(expanded, gs)
== null)) { // the current gamestate is not in the expanded arraylist (nothing is
// returned from the function findNodeWithState)
int newCost =
n.getCost()
+ 1; // returns the cost of exploring that node, and saves is as int newCost
Node newNode =
new Node(
gs, n,
newCost); // newNode is creates as type Node, which consists of the gamestate
// from moveList, the unexpanded node and the cost of exploration
unexpanded.add(newNode); // this newNode is added to the unexpanded list
}
}
}
}
output.println("No solution found"); // outputs no solution found if nothing is found.
}
