package edu.java.chap3;

import java.util.Stack;

/* In the classic problem of the Towers of Hanoi, you have 3 rods and N disks of different sizes which can slide on to any

tower The puzzle starts with disks sorted in ascending order of size from top to bottom (e g , each disk sits on top of an

even larger one) You have the following constraints:

(A) Only one disk can be moved at a time

(B) A disk is slid off the top of one rod onto the next rod

(C) A disk can only be placed on top of a larger disk

Write a program to move the disks from the first rod to the last using Stacks

*/

public class Hanoi {

/**

* @param args

*/

public static void main(String[] args) {

int n = 5;

Tower[] towers = new Tower[n];

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]);

}

}

class Tower {

private Stack<Integer> disks;

private int index;

public Tower(int i ){

this.disks = new Stack<Integer>();

this.index = i;

}

public int index(){

return index;

}

public void add(int d){

if (!disks.isEmpty() && disks.peek()<d){

System.out.println("Cannot put on top of it");

} else {

disks.push(d);

}

}

public void moveTopTo(Tower t){

int top = disks.pop();

t.add(top);

System.out.println("Move"+ top + "from "+this.index()+ "to"+ t.index());

}

public void print() {

System.out.println("tower print+ "+this.index());

for (int i = disks.size() - 1; i >= 0; i--) {

System.out.println(" " + disks.get(i)); }

}

public void moveDisks(int n, Tower destination, Tower buffer) {

if (n > 0) {

moveDisks(n - 1, buffer, destination);

moveTopTo(destination);

buffer.moveDisks(n - 1, destination, this);

}

}

}