/** Helper method to determine if special font is needed. */
public static final boolean isSymbol(int value) {
if (value == MoveEvaluation.minimum()) {
return true;
} else if (value == MoveEvaluation.maximum()) {
return true;
}
return false; // nothing special.
}
/**
* Helper method for converting values into properly visible labels.
*
* <p>These special characters are displayed in Symbol font.
*/
public static final String convert(int value) {
if (value == MoveEvaluation.minimum()) {
return "-inf"; // - INF using an em-dash
} else if (value == MoveEvaluation.maximum()) {
return "inf"; // that is char for INF in Symbol font.
}
return "" + value;
}
/**
* Provides a default evaluation function for the given board state. The evaluation is taken from
* the point of view of a given player AFTER he has made his move.
*
* <p>If the board state is:
*
* <ul>
* <li>a win for the player, then MoveEvaluation.maximum() is returned.
* <li>a win for the opponent, then MoveEvaluation.minimum()
* <li>otherwise, score returned is difference NC(player) - NC(opponent), where NC(x) is the
* number of complete rows, columns or diagonals still open for player x on the board.
* </ul>
*
* @param state The state of the game
* @param ip The player who has just made their move
* @return integer representing board score.
*/
public int score(IGameState state, IPlayer ip) {
TicTacToeState tttState = (TicTacToeState) state;
TicTacToeBoard board = tttState.board();
Player p = (Player) ip;
// we have lost!
int n = numInRow(board, 3, p.getOpponentMark());
if (n > 0) {
return MoveEvaluation.minimum();
}
// we are the champion!
n = numInRow(board, 3, p.getMark());
if (n > 0) {
return MoveEvaluation.maximum();
}
// count number of complete rows/columns/diagonals that are still
// open for a given player.
int n1 = availableRow(board, p.getMark());
int n2 = availableRow(board, p.getOpponentMark());
return n1 - n2;
}