public int MakeTurn(Connect4Board b)
{
int depth = 5;
if (round >= 25) depth = 7;
else if (round >= 32) depth = 100;
double max = -10000.0;
int bestMoveSoFar = 0;
for (int i = 0; i < b.GetNrColumns(); i++)
{
if (b.IsValidMove(i))
{
Connect4Board testBoard = new Connect4Board(b);
testBoard.AddDisc(i, botId);
double moveScore = AlphaBeta(testBoard, depth, -100000.0, 100000.0, false);
//DisplayScore(moveScore, i);
if (moveScore > max)
{
max = moveScore;
bestMoveSoFar = i;
}
}
}
//b.DisplayBoard();
return bestMoveSoFar;
}
public double AlphaBeta(Connect4Board oldBoard, int depth, double alpha, double beta, bool player)
{
if ((depth == 0) || (CheckForWin(oldBoard) != 0 || CheckForDraw(oldBoard)))
{
return Score(oldBoard);
}
if (player)
{
double val = -10000.0;
for (int i = 0; i < oldBoard.GetNrColumns(); i++)
{
if (oldBoard.IsValidMove(i))
{
Connect4Board newBoard = new Connect4Board(oldBoard);
newBoard.AddDisc(i, botId);
val = Math.Max(val, gamma * AlphaBeta(newBoard, depth-1, alpha, beta, !player));
alpha = Math.Max(alpha, val);
if (beta <= alpha) break;
}
}
return alpha;
}
else
{
double val = 10000.0;
for (int i = 0; i < oldBoard.GetNrColumns(); i++)
{
if (oldBoard.IsValidMove(i))
{
Connect4Board newBoard = new Connect4Board(oldBoard);
newBoard.AddDisc(i, botId);
val = Math.Min(val, gamma * AlphaBeta(newBoard, depth-1, alpha, beta, !player));
beta = Math.Min(val, beta);
if (beta <= alpha) break;
}
}
return beta;
}
}
public int MakeTurn(Connect4Board b)
{
double max = -10000.0;
int bestMoveSoFar = 0;
for (int i = 0; i < b.GetNrColumns(); i++)
{
if (b.IsValidMove(i))
{
Connect4Board testBoard = new Connect4Board(b);
testBoard.AddDisc(i, botId);
double moveScore = AlphaBeta(testBoard, depth, -10000.0, 10000.0, false);
if (moveScore > max)
{
max = moveScore;
bestMoveSoFar = i;
}
}
}
return bestMoveSoFar;
}
public Connect4Board(Connect4Board oldBoard)
{
cols = oldBoard.GetNrColumns();
rows = oldBoard.GetNrRows();
board = new int[cols, rows];
for (int i = 0; i < cols; i++)
{
for (int j = 0; j < rows; j++)
{
board[i, j] = oldBoard.GetDisc(i, j);
}
}
}
public int CheckForWin(Connect4Board b)
{
int piece;
//Checking vertically
for (int i = 0; i < b.GetNrColumns(); i++)
{
for (int j = 0; j < b.GetNrRows()-3; j++)
{
if ((piece = b.GetDisc(i, j)) != 0)
{
if (piece == b.GetDisc(i, j+1))
{
if (piece == b.GetDisc(i, j+2))
{
if (piece == b.GetDisc(i, j+3)) return piece;
else j += 2;
}
else j += 1;
}
}
}
}
//Checking horizontally
for (int j = 0; j < b.GetNrRows(); j++)
{
for (int i = 0; i < b.GetNrColumns()-3; i++)
{
if ((piece = b.GetDisc(i, j)) != 0)
{
if (piece == b.GetDisc(i+1, j))
{
if (piece == b.GetDisc(i+2, j))
{
if (piece == b.GetDisc(i+3, j)) return piece;
else i += 2;
}
else i += 1;
}
}
}
}
//Checking diagonally
for (int i = 0; i < b.GetNrColumns()-3; i++)
{
for (int j = 0; j < b.GetNrRows()-3; j++)
{
if ((piece = b.GetDisc(i, j)) != 0)
{
if (piece == b.GetDisc(i + 1, j + 1) && piece == b.GetDisc(i + 2, j + 2) && piece == b.GetDisc(i + 3, j + 3)) return piece;
}
if ((piece = b.GetDisc(i+3, j)) != 0)
{
if (piece == b.GetDisc(i + 2, j + 1) && piece == b.GetDisc(i + 1, j + 2) && piece == b.GetDisc(i, j + 3)) return piece;
}
}
}
return 0;
}
public bool CheckForDraw(Connect4Board b)
{
for (int i = 0; i < b.GetNrColumns(); i++)
{
if (b.IsValidMove(i)) return false;
}
return true;
}
public double EvalBoardPosition(Connect4Board b)
{
double accumScore = 0.0;
//Vertical
for (int i = 0; i < b.GetNrColumns(); i++)
{
for (int j = 0; j < b.GetNrRows()-3; j++)
{
accumScore += EvalSingle(b, i, j, 0, 1, botId);
accumScore -= EvalSingle(b, i, j, 0, 1, 3 - botId);
}
}
//Horizontal
for (int j = 0; j < b.GetNrRows(); j++)
{
for (int i = 0; i < b.GetNrColumns()-3; i++)
{
accumScore += EvalSingle(b, i, j, 1, 0, botId);
accumScore -= EvalSingle(b, i, j, 1, 0, 3 - botId);
}
}
for (int i = 0; i < b.GetNrColumns()-3; i++)
{
for (int j = 0; j < b.GetNrRows()-3; j++)
{
accumScore += EvalSingle(b, i, j, 1, 1, botId);
accumScore -= EvalSingle(b, i, j, 1, 1, 3 - botId);
accumScore += EvalSingle(b, i + 3, j, -1, 1, botId);
accumScore -= EvalSingle(b, i + 3, j, -1, 1, 3 - botId);
}
}
return accumScore;
}
