private NQueensBoard placeQueenAt(int row, int column,
NQueensBoard parentBoard)
{
NQueensBoard newBoard = new NQueensBoard(parentBoard.getSize());
ArrayList queenPositionsOnParentBoard = parentBoard.getQueenPositions();
queenPositionsOnParentBoard.Add(new XYLocation(row, column));
newBoard.setBoard(queenPositionsOnParentBoard);
return(newBoard);
}
private NQueensBoard placeQueenAt(int row, int column,
NQueensBoard parentBoard)
{
NQueensBoard newBoard = new NQueensBoard(parentBoard.getSize());
ArrayList queenPositionsOnParentBoard = parentBoard.getQueenPositions();
queenPositionsOnParentBoard.Add(new XYLocation(row, column));
newBoard.setBoard(queenPositionsOnParentBoard);
return newBoard;
}
public ArrayList getSuccessors(Object state)
{
ArrayList successors = new ArrayList();
NQueensBoard board = (NQueensBoard)state;
int numQueens = board.getNumberOfQueensOnBoard();
int boardSize = board.getSize();
for (int i = 0; i < boardSize; i++)
{
if (!(board.isSquareUnderAttack(new XYLocation(numQueens, i))))
{
NQueensBoard child = placeQueenAt(numQueens, i, board);
successors.Add(new Successor("placeQueenAt " + numQueens + " "
+ i, child));
}
}
return(successors);
}
public int getHeuristicValue(Object state)
{
NQueensBoard board = (NQueensBoard)state;
return(board.getSize() - board.getNumberOfQueensOnBoard());
}
private bool allQueensPlaced()
{
return(board.getNumberOfQueensOnBoard() == board.getSize());
}