public static double alphabetarate(Game root, int depth, double alpha, double beta, bool player)
{
if (depth == 0)
{
return(root.calcRating());
}
//Max phase
if (player)
{
List <StateTransition> moves = root.getAllMoveStates();
if (moves.Count == 0)
{
return(-100);
}
StateTransition selectedMove = moves[0];
foreach (StateTransition move in moves)
{
alpha = Math.Max(alpha, Game.alphabetarate(move.nextState, depth - 1, alpha, beta, !player));
if (beta <= alpha)
{
break;
}
}
return(alpha);
}
//Min phase
else
{
List <Game> rnd = root.getAllRandom();
foreach (Game g in rnd)
{
beta = Math.Min(beta, Game.alphabetarate(g, depth - 1, alpha, beta, !player));
if (beta <= alpha)
{
break;
}
}
return(beta);
}
}
public static double expectimax(Game root, int depth, bool player)
{
double curRating;
if (depth == 0)
{
return(root.calcRating());
}
//Max phase
if (player)
{
double maxRating = 0;
List <StateTransition> moves = root.getAllMoveStates();
if (moves.Count == 0)
{
return(-100);
}
StateTransition selectedMove = moves[0];
foreach (StateTransition move in moves)
{
move.rating = Game.expectimax(move.nextState, depth - 1, !player);
maxRating = Math.Max(maxRating, move.rating);
}
return(maxRating);
}
//Min phase
else
{
double minRating = 10000;
double probability;
List <Game> rnd = root.getAllRandom();
foreach (Game g in rnd)
{
probability = (rnd.IndexOf(g) % 2 == 0) ? 0.9F : 0.1F;
curRating = probability * Game.expectimax(g, depth - 1, !player);
minRating = Math.Min(minRating, curRating);
}
return(minRating);
}
}
void AI_Step()
{
List <StateTransition> moves = oGame.getAllMoveStates();
if (moves.Count == 0)
{
oGame.gameOver = true;
return;
}
StateTransition selectedMove = moves[0];
//int depth = cboDepth.SelectedIndex;
foreach (StateTransition move in moves)
{
switch (currentAlg)
{
case Algorithm.MiniMax:
move.rating = Game.minimax(move.nextState, depth, false);
break;
case Algorithm.AlphaBeta:
move.rating = Game.alphabetarate(move.nextState, depth, float.MinValue, float.MaxValue, false);
break;
case Algorithm.ExpectiMax:
move.rating = Game.expectimax(move.nextState, depth, false);
break;
}
if (selectedMove.rating < move.rating)
{
selectedMove = move;
}
}
oGame.moveBoard(selectedMove.dir);
UpdateGame();
}
