227.Mock Hanoi Tower by Stacks

public class Tower {
private Stack disks;
// create three towers (i from 0 to 2)
public Tower(int i) {
disks = new Stack();
}

// Add a disk into this tower
public void add(int d) {
    if (!disks.isEmpty() && disks.peek() <= d) {
        System.out.println("Error placing disk " + d);
    } else {
        disks.push(d);
    }
}

// @param t a tower
// Move the top disk of this tower to the top of t.
public void moveTopTo(Tower t) {
    // Write your code here
    int temp = disks.pop();
    t.add(temp);
}

// @param n an integer
// @param destination a tower
// @param buffer a tower
// Move n Disks from this tower to destination by buffer tower
public void moveDisks(int n, Tower destination, Tower buffer) {
    // Write your code here
    if (n == 0) return;
    if (n == 1) {
        moveTopTo(destination);
        return;
    }
    moveDisks(n - 1, buffer, destination);
    moveTopTo(destination);
    buffer.moveDisks(n - 1, destination, this);
}

public Stack getDisks() {
    return disks;
}
}
/**
 * Your Tower object will be instantiated and called as such:
 * Tower[] towers = new Tower[3];   
 *  for (int i = 0; i < 3; i++) towers[i] = new Tower(i);
 * for (int i = n - 1; i >= 0; i--) towers[0].add(i);   
 * towers[0].moveDisks(n, towers[2], towers[1]);
 * print towers[0], towers[1], towers[2]
*/