private MNResult EvaluateNode(Move move, bool player, bool debug)
{
int score;
if (!debug)
{
score = evaluation.EvaluateBoard(this.examinedBoard);
//Negate the value
if (player == BLACK)
{
score = -score;
}
}
else
{
Console.Write("What is the score:");
score = Convert.ToInt32(Console.ReadLine());
}
MNResult result = new MNResult(move, score);
return(result);
}
private MNResult AlphaBeta(int depth, int beta, int alpha, Move move, bool player, bool debug = false)
{
//BLACK is max player
bool isMaxPlayer = (player == BLACK) ? true : false;
if (depth == 0)
{
return(EvaluateNode(move, player, debug));
}
List <Move> possibleMoves = null;
if (!debug)
{
possibleMoves = examinedBoard.PossibleMoves(player);
}
else
{
Console.Write("How many moves are there:");
int count = Convert.ToInt32(Console.ReadLine());
possibleMoves = new List <Move>();
for (int i = 0; i < count; i++)
{
Move debugMove = new Move(1, 4, 3, 4, this.examinedBoard);
possibleMoves.Add(debugMove);
}
}
if (possibleMoves.Count == 0)
{
return(EvaluateNode(move, player, debug));
}
//sort later
foreach (Move eleMove in possibleMoves)
{
examinedBoard.MakeMove(eleMove);
bool nextPlayer = !player;
MNResult result = AlphaBeta(depth - 1, beta, alpha, eleMove, nextPlayer, debug);
int value = result.Value;
examinedBoard.UndoMove(eleMove);
//BLACK is Max Player
if (isMaxPlayer)
{
if (value > alpha) //Max Nodes can only make restriction on the lower bound
{
alpha = value;
if (depth == MaxDepth)
{
move = result.Move;
}
}
}
else
{
if (value < beta)
{
beta = value;
if (depth == MaxDepth)
{
move = result.Move;
}
}
}
if (alpha >= beta) //pruning
{
if (isMaxPlayer)
{
return(new MNResult(move, alpha));
}
else
{
return(new MNResult(move, beta));
}
}
}
// Travel all child node, no prunning
if (isMaxPlayer)
{
//value of node is alpha value
return(new MNResult(move, alpha));
}
else
{
//value of min node is beta value
return(new MNResult(move, beta));
}
}