import java.util.Queue;
import java.util.LinkedList;
public class TreeTraverse
{
 private static class Node<T>
 {
  public Node<T> left;
  public Node<T> right;
  public T data;
  public Node(T data)
  {
   this.data = data;
  }
  public Node<T> getLeft()
  {
   return this.left;
  }
  public void setLeft(Node<T> left)
  {
   this.left = left;
  }
  public Node<T> getRight()
  {
   return this.right;
  }
  public void setRight(Node<T> right)
  {
   this.right = right;
  }
 }
 public static void preorder(Node<?> n)
 {
  if (n != null)
  {
   System.out.print(n.data + " ");
   preorder(n.getLeft());
   preorder(n.getRight());
  }
 }
 public static void inorder(Node<?> n)
 {
  if (n != null)
  {
   inorder(n.getLeft());
   System.out.print(n.data + " ");
   inorder(n.getRight());
  }
 }
 public static void postorder(Node<?> n)
 {
  if (n != null)
  {
   postorder(n.getLeft());
   postorder(n.getRight());
   System.out.print(n.data + " ");
  }
 }
 public static void levelorder(Node<?> n)
 {
  Queue<Node<?>> nodequeue = new LinkedList<Node<?>>();
  if (n != null)
   nodequeue.add(n);
  while (!nodequeue.isEmpty())
  {
   Node<?> next = nodequeue.remove();
   System.out.print(next.data + " ");
   if (next.getLeft() != null)
   {
    nodequeue.add(next.getLeft());
   }
   if (next.getRight() != null)
   {
    nodequeue.add(next.getRight());
   }
  }
 }
 public static void main(final String[] args)
 {
  Node<Integer> one = new Node<Integer>(1);
  Node<Integer> two = new Node<Integer>(2);
  Node<Integer> three = new Node<Integer>(3);
  Node<Integer> four = new Node<Integer>(4);
  Node<Integer> five = new Node<Integer>(5);
  Node<Integer> six = new Node<Integer>(6);
  Node<Integer> seven = new Node<Integer>(7);
  Node<Integer> eight = new Node<Integer>(8);
  Node<Integer> nine = new Node<Integer>(9);
  one.setLeft(two);
  one.setRight(three);
  two.setLeft(four);
  two.setRight(five);
  three.setLeft(six);
  four.setLeft(seven);
  six.setLeft(eight);
  six.setRight(nine);
  preorder(one);
  System.out.println();
  inorder(one);
  System.out.println();
  postorder(one);
  System.out.println();
  levelorder(one);
  System.out.println();
 }
}