KeyValuePair <int, CheckersState> MaxValue(CheckersState state, int alpha, int beta, int depth)
{
// Si l'etat est un etat terminal de l'arbre on retourne une valeur
if (state.Terminal || depth >= m_depthMax)
{
return(new KeyValuePair <int, CheckersState>(state.Utility, state));
}
//Debug.WriteLine("Max profondeur : "+depth);
int utility = int.MinValue;
CheckersState bestSuccessor = state;
// Pour tous les successeurs de l'etat on recupere le successeur qui renvoie la plus grande utilite minimum
List <CheckersState> successors = state.Successors();
if (successors.Count == 1 && depth == 0)
{
return(new KeyValuePair <int, CheckersState>(successors[0].Utility, successors[0]));
}
foreach (CheckersState nextState in successors)
{
int successorUtility = MinValue(nextState, alpha, beta, depth + 1).Key;
if (utility < successorUtility)
{
utility = successorUtility;
bestSuccessor = nextState;
}
/*else if (utility == successorUtility)
* {
* int choose = rand.Next(0, 2);
* bestSuccessor = choose > 0 ? bestSuccessor : nextState;
* }*/
if (utility >= beta)
{
//Debug.WriteLine("Fin max profondeur : " + depth + ", utilite : " + utility);
return(new KeyValuePair <int, CheckersState>(utility, bestSuccessor));
}
alpha = Math.Max(alpha, utility);
}
//Debug.WriteLine("Fin max profondeur : " + depth + ", utilite : " + utility);
return(new KeyValuePair <int, CheckersState>(utility, bestSuccessor));
}
/// <summary>
/// Retourne le pire etat successeurs(pour l'agent) a l'etat propose
/// </summary>
/// <param name="state">L'etat propose</param>
/// <param name="depth">La profondeur dans l'arbre a laquelle on se trouve</param>
/// <returns>Le pire etat successeurs</returns>
KeyValuePair <int, CheckersState> MinValue(CheckersState state, int depth)
{ // Si l'etat est un etat terminal de l'arbre on retourne une valeur
if (state.Terminal || depth >= m_depthMax)
{
return(new KeyValuePair <int, CheckersState>(state.Utility, state));
}
int utility = int.MaxValue;
CheckersState bestSuccessor = state;
// Pour tout les successeurs de l'etat on recupere le successeur qui renvoie la plus petite utilite maximum
foreach (CheckersState nextState in state.Successors())
{
int successorUtility = MaxValue(nextState, depth + 1).Key;
if (utility > successorUtility)
{
utility = successorUtility;
bestSuccessor = nextState;
}
}
return(new KeyValuePair <int, CheckersState>(utility, bestSuccessor));
}
