private bool TryPlayThreeInARowFor(SquareContent content, Game game)
{
Square[] emptySquares = game.EmptySquares();
int length = emptySquares.Length;
if (length == 0) // no empty squares left; should not occur, but test anyway
return false;
foreach (Square square in emptySquares)
{
Board tryBoard = game.BoardCopy; // gets a copy of the game board
tryBoard[square] = content;
Line[] linesForSquare = Board.LinesForSquare(square); // get a copy
foreach (Line line in linesForSquare)
{
if (tryBoard.LineSum(line, content) == Game.WinningLineSum)
{
game.Play(square);
return true;
};
};
};
return false;
}
public override bool PlayBestMove(Game game)
{
// strategy 0: no possible moves
if (game.Finished())
return false;
// strategy 1: play a winning move
// find a line that is winning for the player
// optimization:
// only needed when you have played 2 times (and the opponent 1 or 2 times)
// so only if there are 6 or less empty Squares, you need to check for this.
if (TryPlayThreeInARowFor(Game.PlayerToContent(game.CurrentPlayer), game))
{
return true;
}
// strategy 2: play a blocking move
// find a line that is winning for the opponent
if (TryPlayThreeInARowFor(Game.PlayerToContent(game.CurrentOpponent), game))
{
return true;
}
// strategy 3: try to move on a priority square
// we base the priority on the number of lines that each square contains
Square[] emptySquares = game.EmptySquares();
int length = emptySquares.Length;
if (length == 0) // no empty squares left; should not occur, but test anyway
return false;
Square prioritySquare = emptySquares[0];
int linesForPrioritySquareLength = Board.LinesForSquare(prioritySquare).Length;
foreach (Square square in emptySquares)
{
int linesForSquareLength = Board.LinesForSquare(square).Length;
if (linesForSquareLength > linesForPrioritySquareLength)
{
prioritySquare = square;
linesForPrioritySquareLength = linesForSquareLength;
}
}
game.Play(prioritySquare);
return true;
// strategy 4: random move
// not needed any more because we can always find a priority square
//TicTacToePlayer randomPlayer = new RandomTicTacToePlayer();
//randomPlayer.PlayBestMove(game);
}
public override bool PlayBestMove(Game game)
{
if (game.Finished())
return false;
Square[] emptySquares = game.EmptySquares();
int length = emptySquares.Length;
if (length == 0) // no empty squares left; should not occur, but test anyway
return false;
Random random = new Random();
while (true)
{
int value = random.Next() % length;
Square square = emptySquares[value];
game.Play(square);
return true;
};
}