5.10

我不会告诉你，其实我没有明白这道题是干嘛的。

这个题我瞅了很多天了，可是我的脑子里根本塞不进东西去。

最后参考别人的，反正是AC了，以后脑子清楚的时候，一定会回来再看这题的。

public class Tower {
    private Stack<Integer> disks;
    // create three towers (i from 0 to 2)
    public Tower(int i) {
        disks = new Stack<Integer>();
    }
	
    // 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
          t.add(disks.pop());
    }
	
    // @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 == 1){
            moveTopTo(destination);
        }
        if(n >1){
            moveDisks(n-1,buffer,destination);
            moveTopTo(destination);
            buffer.moveDisks(n-1, destination,this);
        }
      
    }

    public Stack<Integer> 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]
*/