public HashSet <Action> actions(System.Object state)
{
EightPuzzleBoard board = (EightPuzzleBoard)state;
HashSet <Action> actions = new HashSet <Action>();
if (board.canMoveGap(EightPuzzleBoard.UP))
{
actions.Add(EightPuzzleBoard.UP);
}
if (board.canMoveGap(EightPuzzleBoard.DOWN))
{
actions.Add(EightPuzzleBoard.DOWN);
}
if (board.canMoveGap(EightPuzzleBoard.LEFT))
{
actions.Add(EightPuzzleBoard.LEFT);
}
if (board.canMoveGap(EightPuzzleBoard.RIGHT))
{
actions.Add(EightPuzzleBoard.RIGHT);
}
return(actions);
}
public BidirectionalEightPuzzleProblem(EightPuzzleBoard initialState) : base(initialState, EightPuzzleFunctionFactory.getActionsFunction(),
EightPuzzleFunctionFactory.getResultFunction(),
new DefaultGoalTest(new EightPuzzleBoard(new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8 })))
{
reverseProblem = new Problem(new EightPuzzleBoard(new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8 }),
EightPuzzleFunctionFactory.getActionsFunction(), EightPuzzleFunctionFactory.getResultFunction(),
new DefaultGoalTest(initialState));
}
public double h(Object state)
{
EightPuzzleBoard board = (EightPuzzleBoard)state;
int retVal = 0;
for (int i = 1; i < 9; i++)
{
XYLocation loc = board.getLocationOf(i);
retVal += evaluateManhattanDistanceOf(i, loc);
}
return(retVal);
}
private int getNumberOfMisplacedTiles(EightPuzzleBoard board)
{
int numberOfMisplacedTiles = 0;
if (!(board.getLocationOf(0).Equals(new XYLocation(0, 0))))
{
numberOfMisplacedTiles++;
}
if (!(board.getLocationOf(1).Equals(new XYLocation(0, 1))))
{
numberOfMisplacedTiles++;
}
if (!(board.getLocationOf(2).Equals(new XYLocation(0, 2))))
{
numberOfMisplacedTiles++;
}
if (!(board.getLocationOf(3).Equals(new XYLocation(1, 0))))
{
numberOfMisplacedTiles++;
}
if (!(board.getLocationOf(4).Equals(new XYLocation(1, 1))))
{
numberOfMisplacedTiles++;
}
if (!(board.getLocationOf(5).Equals(new XYLocation(1, 2))))
{
numberOfMisplacedTiles++;
}
if (!(board.getLocationOf(6).Equals(new XYLocation(2, 0))))
{
numberOfMisplacedTiles++;
}
if (!(board.getLocationOf(7).Equals(new XYLocation(2, 1))))
{
numberOfMisplacedTiles++;
}
if (!(board.getLocationOf(8).Equals(new XYLocation(2, 2))))
{
numberOfMisplacedTiles++;
}
return(numberOfMisplacedTiles);
}
public bool equals(Object o)
{
if (this == o)
{
return(true);
}
if ((o == null) || (this.GetType() != o.GetType()))
{
return(false);
}
EightPuzzleBoard aBoard = (EightPuzzleBoard)o;
for (int i = 0; i < 8; i++)
{
if (this.getPositionOf(i) != aBoard.getPositionOf(i))
{
return(false);
}
}
return(true);
}
public System.Object result(System.Object s, Action a)
{
EightPuzzleBoard board = (EightPuzzleBoard)s;
if (EightPuzzleBoard.UP.Equals(a) &&
board.canMoveGap(EightPuzzleBoard.UP))
{
EightPuzzleBoard newBoard = new EightPuzzleBoard(board);
newBoard.moveGapUp();
return(newBoard);
}
else if (EightPuzzleBoard.DOWN.Equals(a) &&
board.canMoveGap(EightPuzzleBoard.DOWN))
{
EightPuzzleBoard newBoard = new EightPuzzleBoard(board);
newBoard.moveGapDown();
return(newBoard);
}
else if (EightPuzzleBoard.LEFT.Equals(a) &&
board.canMoveGap(EightPuzzleBoard.LEFT))
{
EightPuzzleBoard newBoard = new EightPuzzleBoard(board);
newBoard.moveGapLeft();
return(newBoard);
}
else if (EightPuzzleBoard.RIGHT.Equals(a) &&
board.canMoveGap(EightPuzzleBoard.RIGHT))
{
EightPuzzleBoard newBoard = new EightPuzzleBoard(board);
newBoard.moveGapRight();
return(newBoard);
}
// The Action is not understood or is a NoOp
// the result will be the current state.
return(s);
}
public EightPuzzleBoard(EightPuzzleBoard copyBoard) : this(copyBoard.getState())
{
}
public double h(Object state)
{
EightPuzzleBoard board = (EightPuzzleBoard)state;
return(getNumberOfMisplacedTiles(board));
}
public bool isGoalState(Object state)
{
EightPuzzleBoard board = (EightPuzzleBoard)state;
return(board.Equals(goal));
}