public static Tuple <bool, char> ComputeGameResult(char[,] board, char emptyChar)
{
var boardLines = BoardUtils.GetAllBoardLinesCoordinates(board.GetLength(0));
foreach (var line in boardLines)
{
char c = board[line.First().Item1, line.First().Item2];
if (c == emptyChar)
{
continue;
}
bool win = true;
foreach (var coord in line)
{
if (c != board[coord.Item1, coord.Item2])
{
win = false;
break;
}
}
if (win)
{
return(new Tuple <bool, char>(true, c));
}
}
if (BoardUtils.IsDraw(board, emptyChar))
{
return(new Tuple <bool, char>(true, emptyChar));
}
return(new Tuple <bool, char>(false, emptyChar));
}
protected Tuple <int, int> findWinningMove(char[,] board, char symbol)
{
List <List <Tuple <int, int> > > boardLines = BoardUtils.GetAllBoardLinesCoordinates(boardSize);
foreach (var line in boardLines)
{
int currentLineScore = 0;
int movesToWin = 0;
Tuple <int, int> winCoords = null;
foreach (var coord in line)
{
if (board[coord.Item1, coord.Item2] == symbol)
{
currentLineScore++;
}
else if (board[coord.Item1, coord.Item2] == Engine.EMPTY_CHAR)
{
movesToWin++;
winCoords = coord;
}
}
if (currentLineScore == boardSize - 1 && movesToWin == 1)
{
return(winCoords);
}
}
return(null);
}
public bool IsGameOver()
{
var gameResult = BoardUtils.ComputeGameResult(board, EMPTY_CHAR);
if (gameResult.Item1 && gameResult.Item2 != EMPTY_CHAR)
{
Winner = getWinnerFromSymbol(gameResult.Item2);
}
return(gameResult.Item1);
}
private int minimaxScoreWithCache(char[,] board, char currentSymbol)
{
Tuple <bool, char> result = BoardUtils.ComputeGameResult(board, Engine.EMPTY_CHAR);
if (result.Item1)
{
// win
if (result.Item2 == Symbol)
{
return(10);
}
// loose
else if (result.Item2 != Engine.EMPTY_CHAR)
{
return(-10);
}
// draw
else
{
return(0);
}
}
List <int> scores = new List <int>();
foreach (var move in BoardUtils.GetAllLegalMoves(board, Engine.EMPTY_CHAR))
{
char[,] workingBoard = (char[, ])board.Clone();
workingBoard[move.Item1, move.Item2] = currentSymbol;
string key = GetCustomHash(workingBoard);
if (!cache.ContainsKey(key))
{
IPlayer opponent = PlayerManager.GetInstance().GetOpponent(currentSymbol);
int score = minimaxScoreWithCache(workingBoard, opponent.Symbol);
cache.Add(key, score);
}
scores.Add(cache[key]);
}
// if current player is our IA, we try to maximize the score,
// else minimize it
if (currentSymbol == Symbol)
{
return(scores.Max());
}
else
{
return(scores.Min());
}
}
internal override Tuple <int, int> AskNextMove(char[,] board)
{
Tuple <int, int> bestMove = null;
int bestScore = int.MinValue;
foreach (var move in BoardUtils.GetAllLegalMoves(board, Engine.EMPTY_CHAR))
{
char[,] workingBoard = (char[, ])board.Clone();
workingBoard[move.Item1, move.Item2] = Symbol;
IPlayer opponent = PlayerManager.GetInstance().GetOpponent(Symbol);
int currentScore = minimaxScoreWithCache(workingBoard, opponent.Symbol);
if (currentScore > bestScore)
{
bestScore = currentScore;
bestMove = new Tuple <int, int>(move.Item1, move.Item2);
}
}
return(bestMove);
}
