import java.util.*;
public class GameTreeNode implements PlayConstants {
    static public int nodeCount = 0;
     
    private int value;
    private int type;
    private int bestMove = -1;
    private Position pos;    
    private GameTreeNode[] child = new GameTreeNode[9];  

    public int getBestMove() {
        return bestMove;
    }
    
private GameTreeNode(Position p,
                       int goalMin, int goalMax) {
   nodeCount++; pos = p; type = p.getPlToMv();
   if (p.won() != NONE) { value = p.won(); return; } 
   Iterator<Integer> moves = p.getMoves();
   if (!moves.hasNext()) { value = DRAW; return; } 
   int m;
   if ((m=p.forcedWin(type)) != -1) {
       bestMove = m;
       value = type;
       return;
   }
   if ((m=p.forcedWin(-type)) != -1) {
       bestMove = m;
       child[m] = new GameTreeNode(p.makeMove(m),
                                   goalMin, goalMax);
       value = child[m].value;
       return;
   }
value = -2*type;
while (moves.hasNext()) {
   m = moves.next();
   child[m] = new GameTreeNode(p.makeMove(m),
                               goalMin,goalMax);

   if (type == MIN && child[m].value < value ||
       type == MAX && child[m].value > value) {
       value = child[m].value;
       bestMove = m;

       // update goals
       if (type == MIN && goalMax > value) goalMax=value; 
       if (type == MAX && goalMin < value) goalMin=value; 
       // leave if goal is reached
       if (goalMin >= goalMax) return;
       
}  } // if, while
} // Konstruktor
    public GameTreeNode(Position p) {
        this(p, MIN, MAX);
    }
}