Q3_4.java

import java.util.Stack;

public class Q3_4{
	public static void main(String[] args){
		Tower source = new Tower(new int[] {4,3,2,1},0);
		Tower tool = new Tower(new int[0],1);
		Tower des = new Tower(new int[0],2);
		source.moveTo(des,tool,source.stack.size());
		
	}
}
class Tower{
	Stack<Integer> stack = new Stack<Integer>();
	int index;
	Tower(int[] array, int i){
		for(int x : array){
			stack.push(x);
		}
		index = i;
	}
	
	void moveOne(Tower des){
		des.stack.push(stack.pop());
		System.out.println("move one from tower "+index + " to tower "+des.index);
	}
	
	void moveTo(Tower des, Tower tool, int size){
		if(size == 0) 
		      return;
		moveTo(tool, des, size -1);
		moveOne(des);
		tool.moveTo(des,this,size-1);
	}
}