import java.util.Collections;
import java.util.ArrayList;
import java.util.List;

/**
 * A utility class that encodes a subset of the rules for 
 * the game Yahtzee.
 *
 * <p>A description of the scoring categories can be
 * found on the <a href="http://en.wikipedia.org/wiki/Yahtzee">
 * Yahtzee Wikipedia web page</a>.
 * 
 * @author EECS1011E_W15
 *
 */
public class Yahtzee {

	private Yahtzee() {
		// private and empty by design
		throw new AssertionError();
	}

	/**
	 * The number of six-sided dice used in a standard game of Yahtzee.
	 */
	public static final int NUMBER_OF_DICE = 5;

	/**
	 * Returns <code>true</code> if the list contains a three of a kind.
	 * 
	 * <p>A three of a kind is defined as at least three dice having
	 * the same value.
	 * 
	 * @param dice list of dice
	 * @pre. <code>dice.size() == Yahtzee.NUMBER_OF_DICE</code>
	 * @return <code>true</code> if the list contains a three of a kind
	 */
	public static boolean isThreeOfAKind(List<Die> dice) {
		// implementation not shown
		if (dice.size() != Yahtzee.NUMBER_OF_DICE) {
			throw new IllegalArgumentException("wrong number of dice: " + dice.size());
		}
		List<Die> copy = new ArrayList<Die>(dice);
		Collections.sort(copy);
		boolean result =
				copy.get(0).getValue() == copy.get(2).getValue() ||
				copy.get(1).getValue() == copy.get(3).getValue() ||
				copy.get(2).getValue() == copy.get(4).getValue();

		return result;
	}

}