source: java/ecj/games/scenarios/RandomizedTwoPlayersGameScenario.java

package games.scenarios;

import ec.util.MersenneTwisterFast;
import games.BoardGame;
import games.GameMove;
import games.Player;

import java.util.List;

public class RandomizedTwoPlayersGameScenario implements GameScenario {

        private Player[] players;
        private double[] prob;
        private MersenneTwisterFast random;
        
        public RandomizedTwoPlayersGameScenario(MersenneTwisterFast random, Player[] players, double[] prob) {
                this.players = players;
                this.prob = prob;
                this.random = random;
        }
        
        public int play(BoardGame game) {
                while (!game.endOfGame()) {
                        List<? extends GameMove> moves = game.findMoves();
                        if (!moves.isEmpty()) {
                                GameMove bestMove = null;
                                if (random.nextBoolean(prob[game.getCurrentPlayer()])) {
                                        bestMove = moves.get(random.nextInt(moves.size()));
                                } else {
                                        double bestEval = Double.NEGATIVE_INFINITY;
                                        for (GameMove move : moves) {
                                                double eval = game.evalMove(players[game.getCurrentPlayer()], move);
                                                if (eval > bestEval) {
                                                        bestEval = eval;
                                                        bestMove = move;
                                                }
                                        }
                                }
                                game.makeMove(bestMove);
                        }
                        game.switchPlayer();
                }
                return game.getOutcome();
        }
}