/// <summary>
/// Purpose: Lower the Heuristic value if our queen is put in danger
/// </summary>
/// <param name="boardState"></param>
/// <param name="color"></param>
/// <returns></returns>
private static int PieceSafety(char[] boardState, ChessColor color)
{
int hazardPenalty = 0;
bool white = color == ChessColor.White;
hazardPenalty += FENExtensions.PieceNotSafe(boardState, FENExtensions.GetPiecePos(boardState, white, 'q'), white) ? -400 : 0;
hazardPenalty += FENExtensions.PieceNotSafe(boardState, FENExtensions.GetPiecePos(boardState, white, 'r'), white) ? -200 : 0;
hazardPenalty += FENExtensions.PieceNotSafe(boardState, FENExtensions.GetPiecePos(boardState, white, 'n'), white) ? -150 : 0;
hazardPenalty += FENExtensions.PieceNotSafe(boardState, FENExtensions.GetPiecePos(boardState, white, 'b'), white) ? -155 : 0;
hazardPenalty += FENExtensions.PieceNotSafe(boardState, FENExtensions.GetPiecePos(boardState, white, 'p'), white) ? -40 : 0;
return(hazardPenalty);
}
public static int maxValue(ref char[] board, int depth, bool white, int alpha, int beta, int cutoff, ref Stopwatch timer)
{
TimeSpan maxTime = TimeSpan.FromMilliseconds(5500);
ChessColor color = (white ? ChessColor.White : ChessColor.Black);
int hValue;
if (depth == cutoff)
{
return(Heuristic.GetHeuristicValue(board, color));
}
LightList childrenBoard = FEN.GetAvailableMoves(board, color, false);
int count = childrenBoard.Count;
if (count == 0) //no moves available
{
if (FENExtensions.InCheck(board, white))
{
return(-5000);//checkmate
}
else
{
return(-3000);//stalemate;
}
}
//sort array of moves
int[] Hchildren = new int[count];
for (int idx = 0; idx < count; ++idx)
{
Hchildren[idx] = Heuristic.GetHeuristicValue(childrenBoard[idx], color);
}
sort(ref childrenBoard, ref Hchildren);
int maximumValue = -10000;
int i = 0;
char[] tempBoard = null;
while (i < count && timer.Elapsed < maxTime) //process all the children move
{
tempBoard = childrenBoard[i];
if (timer.Elapsed < maxTime)
{
hValue = minValue(ref tempBoard, depth + 1, !white, alpha, beta, cutoff, ref timer);
}
else
{
return(-9999);
}
if (depth == 1)
{
if (maximumValue == hValue)
{
//choose randomly between current choice and this move
Random rnd = new Random();
int value = rnd.Next(0, 1);
if (value == 0)
{
board = tempBoard;
}
}
else if (hValue > maximumValue)
{
maximumValue = hValue;
board = childrenBoard[i];
}
if (maximumValue >= beta)
{
hValue = maximumValue;
childrenBoard = null;
return(hValue);
}
alpha = Math.Max(alpha, maximumValue);
}
else
{
maximumValue = Math.Max(maximumValue, hValue);
if (maximumValue >= beta)
{
hValue = maximumValue;
childrenBoard = null;
return(hValue);
}
alpha = Math.Max(alpha, maximumValue);
}
++i;
}
childrenBoard = null;
if (timer.Elapsed > maxTime)
{
return(-9999);
}
hValue = maximumValue;
return(hValue);
}
//This min value version is only called at depth 1 when a previously found best move is used to inform the ordering of moves
public static int minValue(ref char[] board, int depth, bool white, int alpha, int beta, int cutoff, char[] best, ref Stopwatch timer)
{
ChessColor color = (white ? ChessColor.White : ChessColor.Black);
int hValue;
LightList equalMoves = new LightList();
LightList childrenBoard = FEN.GetAvailableMoves(board, color, false);
int count = childrenBoard.Count;
if (count == 0)
{ //no moves available
if (FENExtensions.InCheck(board, white))
{
return(-5000);//checkmate
}
else
{
return(-3000);//stalemate
}
}
//sort array of moves
int[] Hchildren = new int[count];
for (int idx = 0; idx < count; ++idx)
{
Hchildren[idx] = Heuristic.GetHeuristicValue(childrenBoard[idx], color);
}
sort(ref childrenBoard, ref Hchildren);
bool found = false;
int indexFound = 0;
for (int idx = 0; idx < count; ++idx)
{
found = true;
for (int index = 0; index < 71; ++index)
{
if (best[index] != childrenBoard[idx][index])
{
found = false;
break;
}
}
if (found == true)
{
indexFound = idx;
break;
}
}
//prioritize previously found best move
if (indexFound != 0) //swap
{
char[] temp;
temp = childrenBoard[0];
childrenBoard.Replace(childrenBoard[indexFound], 0);
childrenBoard.Replace(temp, indexFound);
}
int minimumValue = 10000;
int i = 0;
char[] tempBoard = null;
while (i < count)
{ //process all the children moves
if (depth != cutoff)
{
tempBoard = childrenBoard[i];
hValue = maxValue(ref tempBoard, depth + 1, !white, alpha, beta, cutoff, ref timer);
}
else //get heuristics value
{
hValue = Hchildren[i];
}
if (depth == 1)
{
if (hValue == -5000)
{
board = childrenBoard[i];
childrenBoard = null;
return(hValue);
}
if (minimumValue == hValue)
{
equalMoves.Add(tempBoard);
}
else if (hValue < minimumValue)
{
minimumValue = hValue;
board = childrenBoard[i];
equalMoves.Empty();
equalMoves.Add(board);
}
if (minimumValue <= alpha)
{
board = getRandomMove(equalMoves);
childrenBoard = null;
return(hValue);
}
beta = Math.Min(beta, minimumValue);
}
else
{
minimumValue = Math.Min(minimumValue, hValue);
if (minimumValue <= alpha)
{
hValue = minimumValue;
childrenBoard = null;
return(hValue);
}
beta = Math.Min(beta, minimumValue);
if (minimumValue == -5000)
{
return(-5000);
}
}
++i;
}
hValue = minimumValue;
if (depth == 1)
{
board = getRandomMove(equalMoves);
}
childrenBoard = null;
return(hValue);
}
public static int minValue(ref char[] board, int depth, bool white, int alpha, int beta, int cutoff, ref Stopwatch timer)
{
TimeSpan maxTime = TimeSpan.FromMilliseconds(5500);
int hValue;
LightList equalMoves = new LightList();
ChessColor color = (white ? ChessColor.White : ChessColor.Black);
if (depth == cutoff)
{
return(Heuristic.GetHeuristicValue(board, color));
}
LightList childrenBoard = FEN.GetAvailableMoves(board, color, false);
int count = childrenBoard.Count;
if (count == 0)
{ //no moves available
if (FENExtensions.InCheck(board, white))
{
return(-5000);//checkmate
}
else
{
return(-3000);//stalemate
}
}
//sort array of moves
int[] Hchildren = new int[count];
for (int idx = 0; idx < count; ++idx)
{
Hchildren[idx] = Heuristic.GetHeuristicValue(childrenBoard[idx], color);
}
sort(ref childrenBoard, ref Hchildren);
int minimumValue = 10000;
int i = 0;
char[] tempBoard = null;
while (i < count)
{ //process all the children move
tempBoard = childrenBoard[i];
if (timer.Elapsed < maxTime)
{
hValue = maxValue(ref tempBoard, depth + 1, !white, alpha, beta, cutoff, ref timer);
}
else
{
return(-9999);
}
if (depth == 1)
{
if (hValue == -5000)
{
board = childrenBoard[i];
childrenBoard = null;
return(hValue);
}
if (minimumValue == hValue) //store move into list of moves of same value
{
equalMoves.Add(tempBoard);
}
else if (hValue < minimumValue) //new minimum value, reset the move list
{
minimumValue = hValue;
board = childrenBoard[i];
equalMoves.Empty();
equalMoves.Add(board);
}
if (minimumValue <= alpha)
{
board = getRandomMove(equalMoves);
childrenBoard = null;
return(hValue);
}
beta = Math.Min(beta, minimumValue);
}
else
{
minimumValue = Math.Min(minimumValue, hValue);
if (minimumValue <= alpha)
{
hValue = minimumValue;
childrenBoard = null;
return(hValue);
}
beta = Math.Min(beta, minimumValue);
if (minimumValue == -5000)
{
return(-5000);
}
}
++i;
}
hValue = minimumValue;
if (depth == 1)
{
board = getRandomMove(equalMoves);
}
childrenBoard = null;
if (timer.Elapsed > maxTime)
{
return(-9999);
}
hValue = minimumValue;
return(hValue);
}