Print binary tree bottom to top level wise

Problem

Print a binary tree from bottom to top in level order each level in a separate row. For example,

            Given binary tree is:
                    1
                 /      \
                2        3
              /  \        \
             4   5        6
                        /    \
                       7      8


      The output will be 
7,8,
4,5,6,
2,3,
1

        

Solution

Like the previous program of printing binary tree from bottom to top, in this one we will keep a level marker in the stack to break the lines after a level

Code

import java.util.LinkedList;
import java.util.Stack;

public class PrintBinartyTreeBottomToTop
{
 public static void main(String[] args)
 {
  Node a = new Node(1);
  Node b = new Node(2);
  Node c = new Node(3);
  Node d = new Node(4);
  Node e = new Node(5);
  Node f = new Node(6);
  Node g = new Node(7);
  Node h = new Node(8);
  a.left = b;
  a.right = c;
  b.left = d;
  c.left = e;
  c.right = f;
  f.left = g;
  f.right = h;

  printLevelFromBottomToTop(a);
 }

 private static void printLevelFromBottomToTop(Node root)
 {
  Node levelMarker = new Node(-1);
  LinkedList < node > queue = new LinkedList < node >();
  Stack < node > stack = new Stack < node >();
  queue.add(root);
  queue.add(levelMarker);
  while (!queue.isEmpty())
  {
   Node node = queue.poll();
   stack.push(node);
   if (node == levelMarker)
   {
    if (queue.isEmpty())
     break;
    queue.add(levelMarker);
    continue;
   }

   if (node.right != null)
   {
    queue.add(node.right);
   }
   if (node.left != null)
   {
    queue.add(node.left);
   }
  }
  while (!stack.isEmpty())
  {
   Node node = stack.pop();
   if (node == levelMarker)
   {
    System.out.println();
    continue;
   }
   System.out.print(node.value + "\t ");
  }
 }

 static class Node
 {
  Node left;
  Node right;
  int value;

  public Node(int value)
  {
   this.value = value;
  }
 }
}