COP 3530
Section U03
Spring 2017


                            Homework # 3
                            ============



                                         Due: March 1st, 2017



Add the following 5 methods to the class BinaryNode. Insert your code
 in the BinaryNode class that is on this site and turn in the java file 
of the completed BinaryNode class.

1.   Add the method postPlusIn to the BinaryNode class.

      The method has the header

      public static <T> BinaryNode<T> postPlusIn( T[] post, T[] in)

      and takes as input the postorder and the inorder traversals of a binary tree.
      The method constructs a tree that has these traversals and returns the root 
      of the tree.
      It throws an IllegalArgumentException if it is not possible to construct 
      the tree.
      Assume that the arrays have no duplicate items and no null items.

2.   Add the method

     public void iterativePostOrder()

     to the BinaryNode class.

     The method prints the nodes of the tree with root this in postorder, 
     without using recursion.

3.   Add the method

     public void printByLevels()


     to the BinaryNode class.

     The method prints the nodes of the tree with root this using breadthsearch.
     Hint: Use a queue.


4.  Add the method

    public static <T> BinaryNode<T> levelsPlusIn(T[] in, T[] levels)

    that takes as input the inorder traversal and the traversal by levels and
    reconstructs the tree. Throw an IllegalArgumentException if this cannot
    be done. Again, assume that no array has duplications or null items.


5. Two trees are isomorphic if one of them can be derived from the other
   by swapping some of the left and right children.
   Add the method

   public boolean isomorphic(BinaryNode<T> r)

    to the class BinaryNode. The method returns true if the tree r is isomorphic
   to this and false otherwise. Some of the items may be null. Use the equals
   method to check for equality.