/**
 * When the height is 3, the output is<br/>
 * "A -> B<br/>
 *  A -> C<br/>
 *  B -> C<br/>
 *  A -> B<br/>
 *  C -> A<br/>
 *  C -> B<br/>
 *  A -> B".
 */
public class Hanoi {

    private final int height;
    private final String tower1;
    private final String tower2;
    private final String tower3;

    public Hanoi(final int height,
                 final String tower1,
                 final String tower2,
                 final String tower3) {
        this.height = height;
        this.tower1 = tower1;
        this.tower2 = tower2;
        this.tower3 = tower3;
    }
    public Hanoi(int height) {
        this(height, "A", "B", "C");
    }

    public void execute() {
        moveDisc(height, tower1, tower2, tower3);
    }

    private void moveDisc(final int disk,
                          final String source,
                          final String dest,
                          final String aux) {
        if (disk == 1) {
            System.out.println(String.format("%s -> %s", source, dest));
        }
        else {
            moveDisc(disk - 1, source, aux, dest);
            System.out.println(String.format("%s -> %s", source, dest));
            moveDisc(disk - 1, aux, dest, source);
        }
    }
}