public T PlayNextMove(T currentState, int Depth)
{
double alpha = double.MinValue, beta = double.MaxValue;
MiniMaxItem <T> i = Max(currentState, -1, alpha, beta, Depth);
return(i.Item);
}
public T PlayNextMove(T currentState, int player, int Depth)
{
double alpha = double.MinValue, beta = double.MaxValue;
MiniMaxItem <T> i = Max(currentState, player, alpha, beta, Depth);
Debug.Log("Playing with utility " + i.Utility + " for player " + (player == -1 ? "yellow" : "red") + ":\r\n" + i.Item);
return(i.Item);
}
private MiniMaxItem <T> Min(T Entry, int player, double Alpha, double Beta, int Depth)
{
if (Depth == 0)
{
return(new MiniMaxItem <T>(Entry, gameRules.PredictWinner(Entry, player)));
}
T nextState = default(T);
List <T> entries = gameRules.generateNextStates(Entry, player);
double minUtility = double.MaxValue;
// We don't have any more states to cover, let's calculate the utility and go back:
if (entries.Count == 0)
{
return(new MiniMaxItem <T>(default(T), gameRules.CalculateUtility(Entry, player)));
}
else
{
// We got more states to cover:
foreach (T item in entries)
{
MiniMaxItem <T> cUtility = Max(item, player * -1, Alpha, Beta, Depth - 1);
double ItemUtility = cUtility.Utility;
if (ItemUtility <= Alpha)
{
return(cUtility);
}
if (ItemUtility < minUtility)
{
// We are considering returning this state:
nextState = item;
minUtility = ItemUtility;
}
}
}
return(new MiniMaxItem <T>(nextState, minUtility));
}
private MiniMaxItem <T> Max(T Entry, int player, double Alpha, double Beta, int depth)
{
if (depth == 0)
{
return(new MiniMaxItem <T>(Entry, gameRules.PredictWinner(Entry, player)));
}
T nextState = default(T);
List <T> states = gameRules.generateNextStates(Entry, player);
double maxUtility = double.MinValue;
if (states.Count == 0)
{
return(new MiniMaxItem <T>(default(T), gameRules.CalculateUtility(Entry, player)));
}
else
{
foreach (T item in states)
{
MiniMaxItem <T> cUtility = Min(item, player * -1, Alpha, Beta, depth - 1);
double ItemUtility = cUtility.Utility;
if (ItemUtility >= Beta)
{
return(cUtility);
}
if (ItemUtility > maxUtility)
{
maxUtility = ItemUtility;
nextState = item;
}
if (ItemUtility > Alpha)
{
Alpha = ItemUtility;
}
}
}
return(new MiniMaxItem <T>(nextState, maxUtility));
}
