/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package mcts;

import java.util.Collections;
import java.util.Comparator;

/**
 *
 * @author Lloyd
 */
public class UCT {
    
    public static double calculUCT(int nbVisiteParent, int nbVictoire, int nbVisiteEnfant, double coefficientUCT) {
        if (nbVisiteEnfant == 0) {
            return Integer.MAX_VALUE;
        }
        return ((double) nbVictoire/(double) nbVisiteEnfant + coefficientUCT *  Math.sqrt(Math.log(nbVisiteParent)/(double) nbVisiteEnfant));
    }
    
    public static Noeud trouverNoeudPrometteur(Noeud noeud, double coefficient) {
        int nbVisiteParent = noeud.getEtat().getNbVisite();
        Noeud noeudPrometteur = null;
        double uctNoeudPrometteur = Integer.MIN_VALUE;
        
        for (Noeud enfant : noeud.getListeEnfant()) {
            int nbVictoireEnfant = enfant.getEtat().getNbVictoire();
            int nbVisiteEnfant = enfant.getEtat().getNbVisite();
            double valeurUCTenfant = calculUCT(nbVisiteParent, nbVictoireEnfant, nbVisiteEnfant, coefficient); 
                    
            if (valeurUCTenfant > uctNoeudPrometteur) {
                uctNoeudPrometteur = valeurUCTenfant;
                noeudPrometteur = enfant;
            }
        }
        
        return noeudPrometteur;
    }
    
    
    /* // no such element exeption
    public static Noeud trouverMeilleurNoeud(Noeud noeud, double coefficient) {
        int nbVisiteParent = noeud.getEtat().getNbVisite();
        return Collections.max(
          noeud.getListeEnfant(),
          Comparator.comparing(c -> calculUCT(nbVisiteParent, c.getEtat().getNbVictoire(), c.getEtat().getNbVisite(), coefficient)));
    }
    */
}