/// <summary>
/// Performs the tree search.
/// </summary>
/// <param name="rootState"></param>
/// <param name="maxIterations"></param>
/// <param name="randomizeState"></param>
/// <returns></returns>
internal static TreeNode Search(PlayingState rootState, int maxIterations = int.MaxValue, bool randomizeState = true)
{
var rootNode = new TreeNode();
HandRandomizer randomizer = null;
if ((randomizeState) && (rootState.NeedRandomize()))
{
randomizer = new HandRandomizer(rootState);
}
for (var i = 0; i < maxIterations; i++)
{
var node = rootNode;
// 1. Determinize.
var state = rootState.CloneAndRandomize(randomizer);
// 2. Select.
var validMoves = state.GetValidMoves();
while ((validMoves != 0) && (node.GetUntriedMoves(validMoves) == 0)) // The node is fully expanded and non-terminal.
{
node = node.UcbSelectChild(validMoves);
state.DoMove(node.Move);
validMoves = state.GetValidMoves();
}
// 3. Expand.
var untriedMoves = node.GetUntriedMoves(validMoves);
if (untriedMoves != 0)
{
var randomMove = GetRandomMove(untriedMoves, state);
var activeIndex = state.ActiveIndex;
state.DoMove(randomMove);
node = node.AddChild(randomMove, activeIndex);
}
// 4. Simulate.
validMoves = state.GetValidMoves();
while (validMoves != 0)
{
var randomMove = GetRandomMove(validMoves, state);
state.DoMove(randomMove);
validMoves = state.GetValidMoves();
}
// 5. Backpropagate.
while (node != null)
{
node.UpdateStatistics(state);
node = node.Parent;
}
}
return(rootNode.GetBestChild());
}
/// <summary>
/// Performs the tree search.
/// </summary>
/// <param name="rootState"></param>
/// <param name="maxIterations"></param>
/// <param name="randomizeState"></param>
/// <returns></returns>
internal static TreeNode Search(PlayingState rootState, int maxIterations = int.MaxValue, bool randomizeState = true)
{
var rootNode = new TreeNode();
HandRandomizer randomizer = null;
if ((randomizeState) && (rootState.NeedRandomize()))
randomizer = new HandRandomizer(rootState);
for (var i = 0; i < maxIterations; i++)
{
var node = rootNode;
// 1. Determinize.
var state = rootState.CloneAndRandomize(randomizer);
// 2. Select.
var validMoves = state.GetValidMoves();
while ((validMoves != 0) && (node.GetUntriedMoves(validMoves) == 0)) // The node is fully expanded and non-terminal.
{
node = node.UcbSelectChild(validMoves);
state.DoMove(node.Move);
validMoves = state.GetValidMoves();
}
// 3. Expand.
var untriedMoves = node.GetUntriedMoves(validMoves);
if (untriedMoves != 0)
{
var randomMove = GetRandomMove(untriedMoves, state);
var activeIndex = state.ActiveIndex;
state.DoMove(randomMove);
node = node.AddChild(randomMove, activeIndex);
}
// 4. Simulate.
validMoves = state.GetValidMoves();
while (validMoves != 0)
{
var randomMove = GetRandomMove(validMoves, state);
state.DoMove(randomMove);
validMoves = state.GetValidMoves();
}
// 5. Backpropagate.
while (node != null)
{
node.UpdateStatistics(state);
node = node.Parent;
}
}
return rootNode.GetBestChild();
}
/// <summary>
/// Returns a clone of the state replacing closed (not visible) hands with random card distributions.
/// </summary>
/// <param name="randomizer">Null to clone without randomizing.</param>
/// <returns></returns>
internal PlayingState CloneAndRandomize(HandRandomizer randomizer)
{
PlayingState clone = Clone();
if (randomizer != null)
{
randomizer.Randomize();
}
return(clone);
}
private static Move GetRandomMove(int cards, PlayingState state)
{
if (!state.IsActiveHandOpen)
{
return(GetRandomCard(cards));
}
else
{
return(GetRandomGroup(cards, state.Discards));
}
}
private PlayingState Clone()
{
var clone = new PlayingState(mContext);
for (int i = 0; i < HandCount; i++)
{
clone.mHands[i] = mHands[i].Clone();
}
clone.mActiveIndex = mActiveIndex;
clone.mLeadingSuit = mLeadingSuit;
clone.mDiscards = mDiscards;
return(clone);
}
internal HandRandomizer(PlayingState state)
{
mState = state;
CalculateCardSets();
}
internal HandRandomizer(PlayingState state)
{
mState = state;
CalculateCardSets();
}
/// <summary>
/// Updates the statistics for this node using the specified state.
/// </summary>
/// <param name="state"></param>
internal void UpdateStatistics(PlayingState state)
{
VisitCount++;
mTotalValue += state.Evaluate(ActiveIndex);
}
private PlayingState Clone()
{
var clone = new PlayingState(mContext);
for (int i = 0; i < HandCount; i++)
clone.mHands[i] = mHands[i].Clone();
clone.mActiveIndex = mActiveIndex;
clone.mLeadingSuit = mLeadingSuit;
clone.mDiscards = mDiscards;
return clone;
}
/// <summary>
/// Updates the statistics for this node using the specified state.
/// </summary>
/// <param name="state"></param>
internal void UpdateStatistics(PlayingState state)
{
VisitCount++;
mTotalValue += state.Evaluate(ActiveIndex);
}
private static Move GetRandomMove(int cards, PlayingState state)
{
if (!state.IsActiveHandOpen)
return GetRandomCard(cards);
else
return GetRandomGroup(cards, state.Discards);
}
