We recall that the coPreOrder traversal is like the preOrder except that we swap

Question

  We recall that the coPreOrder traversal is like the preOrder except that we swap the calls to the left and right subtrees. The method below prints the nodes of a binary tree in co-preorder      // print the tree elements in co-preorder     public void printInCoPreOrder()     {         System.out.println(element); // print the root         if (right != null)             right.printInCoPreOrder(); // traverse the right subtree         if (left != null)             left.printInCoPreOrder(); // traverse the left subtree     }  Write the iterative method  public void iterativePrintInCoPreOrder()  that prints the elements of the tree in co-preorder, by removing the recursive calls from printInCoPreOrder.  

Explanation / Answer

public void iterativePrintInCoPreOrder()
{
   if( root == null ) return;
     
   Stack<Node> stack = new Stack<Node>( );
   stack.push( root );
     
   while( ! stack.isEmpty( ) ) {
   Node current = stack.pop( );
   if( current.right != null ) stack.push( current.right );
   if( current.left != null ) stack.push( current.left );
   System.out.println( current.element);
   }
   }

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