private MoveScore <T, int> AlphaBeta(ITree <T> tree, MoveScore <T, int> alpha, MoveScore <T, int> beta, Switch <int> player)
{
Enter(tree);
MoveScore <T, int> result;
if (_depthCounter.CurrentDepth >= _maxDepth || tree.IsLeaf || LongRunningProcess.Current.IsCancellationRequested)
{
result = new MoveScore <T, int>
{
Score = _valuer.GetValue(tree.Node),
Move = tree.Node,
Depth = _depthCounter.CurrentDepth
};
}
else
{
if (player.Is(MAX_PLAYER))
{
var children = tree.Children;
foreach (var child in children)
{
// var graph = child.Node;
alpha = alpha.Max(AlphaBeta(child, alpha, beta, player.Swap()));
if (beta.Score <= alpha.Score)
{
CuttoffsCount++;
break;
}
if (LongRunningProcess.Current.IsCancellationRequested)
{
break;
}
}
result = alpha;
}
else
{
var children = tree.Children;
foreach (var child in children)
{
// var graph = child.Node;
beta = beta.Min(AlphaBeta(child, alpha, beta, player.Swap()));
if (beta.Score <= alpha.Score)
{
CuttoffsCount++;
break;
}
if (LongRunningProcess.Current.IsCancellationRequested)
{
break;
}
}
result = beta;
}
}
Leave(tree);
return(result);
}
public static MoveScore <T, int> Min <T>(this MoveScore <T, int> arg1, MoveScore <T, int> arg2)
{
if (arg1.Score < arg2.Score)
{
return(arg1);
}
if (arg1.Score == arg2.Score)
{
return(arg1.Depth <= arg2.Depth ? arg1 : arg2);
}
return(arg2);
}
public void Run <TTree>(TTree tree) where TTree : ITree <T>
{
var alpha = new MoveScore <T, int> {
Score = int.MinValue, Depth = int.MaxValue
};
var beta = new MoveScore <T, int> {
Score = int.MaxValue, Depth = int.MaxValue
};
var currentPlayer = new Switch <int>(MIN_PLAYER, MAX_PLAYER);
BestMove = AlphaBeta(tree, alpha, beta, currentPlayer.Swap());
}
