// Runs an entire game using a parallelized version of iterative deepening minimax
private Move ParallelIterativeDeepening(State state, int timeLimit, Deck deck)
{
Move bestMove = new PlayerMove();
List<Move> moves = state.GetMoves(deck);
ConcurrentBag<Tuple<double, Move>> scores = new ConcurrentBag<Tuple<double, Move>>();
if (moves.Count == 0)
{
// game over
return bestMove;
}
// create the resulting states before starting the threads
List<State> resultingStates = new List<State>();
foreach (Move move in moves)
{
State resultingState = state.ApplyMove(move);
resultingStates.Add(resultingState);
}
Parallel.ForEach(resultingStates, resultingState =>
{
double score = IterativeDeepening(resultingState, timeLimit, deck.Clone()).Score;
scores.Add(new Tuple<double, Move>(score, resultingState.GeneratingMove));
});
// find the best score
double highestScore = Double.MinValue;
foreach (Tuple<double, Move> score in scores)
{
PlayerMove move = (PlayerMove)score.Item2;
if (score.Item1 > highestScore)
{
highestScore = score.Item1;
bestMove = score.Item2;
}
}
return bestMove;
}
// Time limited MCTS
private Node TimeLimited(State rootState, int timeLimit, Stopwatch timer, Deck deck)
{
Node rootNode = new Node(null, null, rootState, deck);
while (true)
{
if (timer.ElapsedMilliseconds > timeLimit)
{
if (FindBestChild(rootNode.Children) == null && !rootNode.state.IsGameOver())
{
timeLimit += 10;
timer.Restart();
}
else
{
return rootNode;
}
}
Node node = rootNode;
State state = rootState.Clone();
Deck clonedDeck = deck.Clone();
// 1: Select
while (node.UntriedMoves.Count == 0 && node.Children.Count != 0)
{
node = node.SelectChild();
state = state.ApplyMove(node.GeneratingMove);
if (node.GeneratingMove is ComputerMove)
{
clonedDeck.Remove(((ComputerMove)node.GeneratingMove).Card);
if (clonedDeck.IsEmpty()) clonedDeck = new Deck();
}
}
// 2: Expand
if (node.UntriedMoves.Count != 0)
{
Move randomMove = node.UntriedMoves[random.Next(0, node.UntriedMoves.Count)];
if (randomMove is ComputerMove)
{
if (clonedDeck.IsEmpty()) clonedDeck = new Deck();
clonedDeck.Remove(((ComputerMove)randomMove).Card);
state = state.ApplyMove(randomMove);
node = node.AddChild(randomMove, state, clonedDeck);
}
else
{
state = state.ApplyMove(randomMove);
node = node.AddChild(randomMove, state, clonedDeck);
}
}
// 3: Simulation
while (state.GetMoves(clonedDeck).Count != 0)
{
Move move = state.GetRandomMove(clonedDeck);
if (move is ComputerMove)
{
if (clonedDeck.IsEmpty()) clonedDeck = new Deck();
clonedDeck.Remove(((ComputerMove)move).Card);
state = state.ApplyMove(move);
}
else
{
state = state.ApplyMove(move);
}
}
// 4: Backpropagation
while (node != null)
{
node.Update(state.GetResult());
node = node.Parent;
}
}
}