private byte[] PredictBestMove(int depth, OthelloGame game, BoardStates player)
{
byte[] bestMove = new byte[] { byte.MaxValue, byte.MaxValue };
List <byte[]> moves = game.GetPossiblePlayList();
double bestScore = int.MinValue + 1;
if (game.GetPieceCount(BoardStates.empty) > 58)//first two moves, don't compute
{
return(OpeningMove(player, game));
}
else if (moves.Count == 1) //don't compute if there is only 1 move
{
return(moves[0]);
}
foreach (byte[] move in moves)
{
OthelloGame testGame = game.DeepCopy();
testGame.MakeMove(move);
double thisScore = MinimaxAlphaBeta(testGame, depth - 1, double.MinValue, double.MaxValue, player);
if (thisScore > bestScore)
{
bestScore = thisScore;
bestMove = move;
}
}
return(bestMove);
}
public static OthelloGame GetReflectedAcrossA1H8(OthelloGame game)
{
OthelloGame newGame = game.DeepCopy();
for (int i = 0; i <= game.GetMovesMade(); i++)
{
for (int j = 0; j < BOARD_SIZE; j++)
{
for (int k = 0; k < BOARD_SIZE; k++)
{
if (game.BoardHistory[i] != null)
{
newGame.BoardHistory[i][j, k] = game.BoardHistory[i][k, j];
}
}
}
}
for (int i = 0; i < BOARD_SIZE; i++)
{
for (int j = 0; j < BOARD_SIZE; j++)
{
newGame.Board[i, j] = game.Board[j, i];
}
}
return(newGame);
}
public static OthelloGame GetInverseGame(OthelloGame game)
{
OthelloGame newGame = game.DeepCopy();
for (int i = 0; i <= game.GetMovesMade(); i++)
{
for (int j = 0; j < BOARD_SIZE; j++)
{
for (int k = 0; k < BOARD_SIZE; k++)
{
if (game.BoardHistory[i] != null)
{
newGame.BoardHistory[i][j, k] = OpposingPlayer(game.BoardHistory[i][j, k]);
}
}
}
}
for (int i = 0; i < BOARD_SIZE; i++)
{
for (int j = 0; j < BOARD_SIZE; j++)
{
newGame.Board[i, j] = OpposingPlayer(game.Board[i, j]);
}
}
return(newGame);
}
public static OthelloGame GetHalfPiRotation(OthelloGame game)
{
OthelloGame newGame = game.DeepCopy();
for (int i = 0; i <= game.GetMovesMade(); i++)
{
for (int j = 0; j < BOARD_SIZE; j++)
{
for (int k = 0; k < BOARD_SIZE; k++)
{
if (game.BoardHistory[i] != null)
{
newGame.BoardHistory[i][j, k] = game.BoardHistory[i][BOARD_SIZE - k - 1, j];
}
}
}
}
for (int i = 0; i < BOARD_SIZE; i++)
{
for (int j = 0; j < BOARD_SIZE; j++)
{
newGame.Board[i, j] = game.Board[BOARD_SIZE - j - 1, i];
}
}
return(newGame);
}
private double MinimaxAlphaBeta(OthelloGame board, int depth, double a, double b, BoardStates player)// bool isMaxPlayer)
{
// The heart of our AI. Minimax algorithm with alpha-beta pruning to speed up computation.
// Higher search depths = greater difficulty.
//from oliverzh200/reversi https://github.com/oliverzh2000/reversi
if (depth == 0 || board.GameComplete)
{
return(HeuristicEval(player, board));
}
double bestScore = double.MinValue;
List <byte[]> validMoves = board.GetPossiblePlayList();
if (validMoves.Count > 0)
{
foreach (byte[] move in validMoves)
{
OthelloGame childBoard = board.DeepCopy();
childBoard.MakeMove(move);
double nodeScore = MinimaxAlphaBeta(childBoard, depth - 1, a, b, player);
bestScore = Math.Max(bestScore, nodeScore);
a = Math.Max(bestScore, a);
if (b <= a) //Prune
{
break;
}
}
}
else
{
return(MinimaxAlphaBeta(board, depth, a, b, player));
}
return(bestScore);
}
private byte[] PredictBestMove(int depth, OthelloGame game, BoardStates player)
{
byte[] bestMove = new byte[] { byte.MaxValue, byte.MaxValue };
List <byte[]> moves = game.GetPossiblePlayList();
double bestScore = int.MinValue + 1;
foreach (byte[] move in moves)
{
OthelloGame testGame = game.DeepCopy();
testGame.MakeMove(move);
double thisScore = MinimaxAlphaBeta(testGame, depth - 1, double.MinValue, double.MaxValue, player);
if (thisScore > bestScore)
{
bestScore = thisScore;
bestMove = move;
}
}
if ((bestMove[0] == byte.MaxValue || bestMove[1] == byte.MaxValue) && moves.Count > 0)
{//All moves are valued at -inf, return one of em
return(moves[0]);
}
return(bestMove);
}
