// MINIMAX FUNCTION
public Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> > Minimax(GameBoard <counters> board, counters counter, int ply, Tuple <int, int> positions, bool mmax, GameBoard <int> scoreBoard, ref int cont, int alpha, int beta)
{
// decs
counters us = Flip(counter);
int ourindex = 1;
List <Tuple <int, int> > availableMoves = getAvailableMoves(board, positions);
// create new list of Tuple<int,int>
List <Tuple <int, Tuple <int, int> > > result_list = new List <Tuple <int, Tuple <int, int> > >();
int bestScore = mmax ? -1001 : 1001;
int score = Consts.MIN_SCORE; // current score of move
Tuple <int, int> Move = new Tuple <int, int>(0, 0);
Tuple <int, int> bestMove = new Tuple <int, int>(1, 1); // best move with score// THRESHOLD <=============
// add assertion here
// decs for random move
Random rnd = new Random();
int randMoveX = rnd.Next(1, 7); // creates a number between 1 and 7
int randMoveY = rnd.Next(1, 7); // creates a number between 1 and 7
Tuple <int, int> randMove = new Tuple <int, int>(randMoveX, randMoveY);
// check win
if (availableMoves.Count == 0)
{
return(new Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> >(10, positions, board, scoreBoard));
}
else if (Win(board, counter))
{
return(new Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> >(1000, positions, board, scoreBoard));
}
else if (Win(board, this.otherCounter))
{
return(new Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> >(-1000, positions, board, scoreBoard));
}
if (FindTwoInARow(board, counter) && Two(board, counter) && board[Move.Item1, Move.Item2] == counters.EMPTY)
{
return(new Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> >(100, positions, board, scoreBoard));
}
else if (FindTwoInARow(board, this.otherCounter) && Two(board, this.otherCounter) && board[Move.Item1, Move.Item2] == counters.EMPTY)
{
return(new Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> >(-100, positions, board, scoreBoard));
}
else if (FindOneInARow(board, ourindex, this.otherCounter) && One(board, counter) && board[Move.Item1, Move.Item2] == counters.EMPTY)
{
return(new Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> >(100, positions, board, scoreBoard));
}
else if (FindOneInARow(board, ourindex, this.otherCounter) && One(board, this.otherCounter) && board[Move.Item1, Move.Item2] == counters.EMPTY)
{
return(new Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> >(-100, positions, board, scoreBoard));
}
// CHECK DEPTH
else if (ply > maxPly)
{
score = EvalCurrentBoard(board, scoreBoard, ourindex, us); // call stat evaluation func - takes board and player and gives score to that player
return(new Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> >(score, positions, board, scoreBoard));
}
// Console.WriteLine("HWL: Is this line reached?");
// Console.ReadLine(); // HWL: even with a ReadLine here, the program runs to the end
// place random move
if (board.IsEmpty()) // if board is empty then play random move
{
// decide scoring for random move
score = EvalForWin(board, ourindex, us); // 1 for win, 0 for unknown
// assign two score
if (FindTwoInARow(board, us)) // player win?
{
score = 100; // twoinrow confirmed
}
if (FindTwoInARow(board, us + 1)) // twoinrow opponent?
{
score = -100; // twoinrow confirmed
}
if (FindOneInARow(board, ourindex, us)) // oneinrow?
{
score = 10; // oneinrow confirmed
}
if (FindOneInARow(board, ourindex, us + 1)) // oneinarow opponent?
{
score = -10; // oneinrow confirmed
}
// MakeRandomMove(board, counter, ply, positions, !mmax, scoreBoard, ref cont);
// Console.ReadLine();
return(new Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> >(score, positions, board, scoreBoard));
}
GameBoard <counters> copy;
// make copy original board
copy = board.Clone(); // make copy board
// copy.DisplayBoard(); // display copy board
// cell priority - favour centre and corners
for (int i = 0; i < availableMoves.Count; i++)
{
Move = availableMoves[i]; // current move
// cell priority - favour centre and corners
// HWL: where do you actual place the piece for the position in Move? you don't do this here, just pass Move to the call of Minimax below; in the recursive call you then overwrite the input argument with a random move (see comment at start of Minimax; so you are actually not considering Move at all!
// HWL: try placing the piece here, and below just use the score
copy[Move.Item1, Move.Item2] = counter; // place counter
// GameBoard board0 = MakeMove(board, move); // copies board - parallel ready
// ************************************************************************************************
// ************************************************************************************************
// ************************************** MAIN MINIMAX WORK ***************************************
// ************************************************************************************************
// ************************************************************************************************
// list defined in Minimax declarations
Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> > result = Minimax(copy, Flip(counter), ply + 1, Move, !mmax, scoreBoard, ref cont, alpha, beta); /* swap player */ // RECURSIVE call
// trying to prevent preventing cell overwrite
copy[Move.Item1, Move.Item2] = counters.EMPTY; /* counter; */ // HWL: remove counter that was tried in this iteration
// GameBoard board0 = MakeMove(board, move); // copies board - parallel ready
score = -result.Item1; // assign score
positions = result.Item2; // present position (x,y)
// list of all result - list of possible result Tuple<int, int>
result_list.Add(new Tuple <int, Tuple <int, int> >(score, positions));
// assign score to correct cell in score
scoreBoard[result.Item2.Item1, result.Item2.Item2] = score;
// HWL: summarise the result of having tried Move, print the assoc scoreboard and check that the matching move is the one for the highest score on the board
/* Console.WriteLine(mmax.ToString() +
* " **HWL (ply={0}) Trying Move ({4},{5}) gives score {1} and position ({2},{3}) [[so far bestScore={6}, bestMove=({7},{8})",
* ply, score, result.Item2.Item1, result.Item2.Item2, Move.Item1, Move.Item2,
* bestScore, bestMove.Item1, bestMove.Item2);
*/
// scoreBoard.DisplayBoard();
if (score == Consts.MIN_SCORE || score == Consts.MAX_SCORE)
{
/* Console.WriteLine("**HWL CLAIM: putting piece {0} at position ({1},{2}) gives 3-in-a-row:",
* counter, Move.Item1, Move.Item2);
*/
}
// ************************************************************************************************
// ************************************************************************************************
// ******************************** END OF MAIN MINIMAX WORK **************************************
// ************************************************************************************************
// ************************************************************************************************
// ************************************************************************************************
// ************************* WHEN TO MAXIMISE, WHEN TO MINIMISE ***********************************
// ******************************* WITH ALPHA-BETA PRUNING ****************************************
// ************************************************************************************************
// ************************************************************************************************
// if maximising
if (/* true HWL || */ mmax)
{
alpha = score;
if (score > bestScore)
{
bestMove = Move;
bestScore = score;
}
if (alpha > bestScore)
{
bestMove = Move;
bestScore = alpha;
}
}
// if minimising
else
{
if (bestScore > score)
{
bestMove = Move;
bestScore = score;
}
if (beta <= alpha)
{
bestScore = alpha;
}
return(new Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> >(bestScore, positions, board, scoreBoard));
}
// ************************************************************************************************
// ************************************************************************************************
// ********************* END OF WHEN TO MAXIMISE, WHEN TO MINIMISE ********************************
// ******************************* WITH ALPHA-BETA PRUNING ****************************************
// ************************************************************************************************
cont++; // increment positions visited
}
return(new Tuple <int, Tuple <int, int>, GameBoard <counters>, GameBoard <int> >(bestScore, bestMove, board, scoreBoard)); // return
}