import java.util.LinkedList;
import java.util.List;

public class MCTSNode {

    //...
    private List<MCTSNode> sons;

    public double getUCB(double C, int totalParents){
        if (totalVisits == 0) return Double.MAX_VALUE;
        if (state.getCurrentPlayer() == 1) return totalScore / totalVisits + C * Math.sqrt(Math.log(totalParents) / totalVisits);
        return -totalScore / totalVisits + C * Math.sqrt(Math.log(totalParents) / totalVisits);
    }

    public boolean isLeaf(){
        return sons == null;
    }

    public List<MCTSNode> getSons() {
        return sons;
    }

    public MCTSNode selectSon(double C){
        double bestUCB = -Double.MAX_VALUE;
        MCTSNode bestState = null;
        for (MCTSNode node: sons){
            double ucb = node.getUCB(C, totalVisits);
            if (ucb > bestUCB){
                bestUCB = ucb;
                bestState = node;
            }
        }
        return bestState;
    }

    public MCTSNode selectLeaf(double C){
        if (this.isLeaf()) return this;
        return selectSon(C).selectLeaf(C);
    }
}