public int MonteCarloSearch(Board rootState, double searchTimer)
{
//Check if we can find a winning move in one move
string deb = "";
if (true)
{
int winCheck = GetHighestValueMove(rootState, 1);
if (winCheck == (rootState.width * rootState.width) / 2)
{
return((rootState.width * rootState.width) / 2);
}
Board copy = new Board(rootState);
copy.ChangeSquare(winCheck);
int value = rootState.blackTurn ? EvaluateBoard(copy) : -EvaluateBoard(copy);
deb += "Highest 1 ply value move is: " + winCheck.ToString() + ", value " + value.ToString() + ".\n ";
if (value > 9999)
{
rootState.DebugWrite(deb);
return(winCheck);
}
}
Node root = new Node(rootState.lastSquare, null, rootState, 1);
Stopwatch s = new Stopwatch();
s.Start();
while (s.Elapsed.Seconds < searchTimer)
{
Node node = root;
Board state = new Board(rootState);
//Select
while (node.untriedMoves.Count == 0 && node.nodes.Count != 0)
{
node = NodeSelection(node);
state.ChangeSquare(node.move);
state.EndTurn();
}
//Expand
if (node.untriedMoves.Count != 0)
{
int move = node.GetRandomMove();
state.ChangeSquare(move);
state.EndTurn();
node = node.AddChild(move, state);
}
//Rollout
int lastMove = node.move;
while (EvaluateBoard(state) == 0)
{
//int move = RootAlphaBeta(int.MinValue, int.MaxValue, state, 2);
int move = GetHighestValueMove(state, 1);
state.ChangeSquare(move);
state.EndTurn();
lastMove = move;
}
//Backpropagate
int result = state.CheckWin(lastMove);
while (node != null)
{
node.games++;
if (result == -1)
{
node.wins += 0.4;
}
else if ((result == 1 && rootState.blackTurn) || (result == 2 && !rootState.blackTurn))
{
node.wins += 1;
}
else
{
node.wins += 0;
}
node = node.parent;
}
}
int bestI = 0;
double bestValue = double.MinValue;
for (int i = 0; i < root.nodes.Count; i++)
{
double val = root.nodes[i].games * (root.nodes[i].wins / root.nodes[i].games);
if (val > bestValue)
{
deb += "Move: " + root.nodes[i].move.ToString() + " has Wins " + root.nodes[i].wins.ToString("0.0") + ", games " + root.nodes[i].games.ToString() + ", = " + (root.nodes[i].wins / root.nodes[i].games).ToString("0.000") + ".\n ";
bestI = i;
bestValue = val;
}
}
rootState.DebugWrite(deb);
//rootState.DebugWrite("Done finding move from " + root.nodes.Count.ToString() + " available.");
return(root.nodes[bestI].move);
}
