public class BST<Key extends Comparable<Key>, Value>
{
   /* ===========================
      Node structure
      =========================== */
   private class Node
   {
      private Key key;
      private Value val;
      private Node left;
      private Node right;

      public Node(Key key, Value val)
      {
	 this.key = key;
	 this.val = val;
      }
   }

   private Node root;	// References the root node of the BST

   public void put(Key key, Value val)
   {
      root = put(root, key, val);
   }

   public Node put(Node x, Key key, Value val)
   {
      if ( x == null )
         return new Node( key, val );

      if ( key.compareTo( x.key ) < 0 )
      {  // (key value) goes in left subtree

         x.left = put( x.left, key, val );
      }
      else if ( key.compareTo( x.key ) > 0 )
      {  // (key value) goes in rightsubtree

         x.right = put( x.right, key, val );
      }
      else 
      {  // ( key == x.key, we replace value in x )

         x.val = val;
      }

      return x;
   }


   public Value get(Key key)
   {
       Node curr_node;   // Help variable

       /* --------------------------------------------
	  Find the node with key == "key" in the BST
          -------------------------------------------- */

       curr_node = root;  // Always start at the root node

       while ( curr_node != null )
       {
          if ( key.compareTo( curr_node.key ) < 0 )
	  {
	     curr_node = curr_node.left;   // Continue search in left subtree
	  }
          else if ( key.compareTo( curr_node.key ) > 0 )
	  {
	     curr_node = curr_node.right;  // Continue search in right subtree
	  }
          else 
	  {
	     // key == curr_node.key, return the val in the node curr_node
	     return curr_node.val;
	  }
       }

       // "Key" Not found !!
       return null;
   }


   public void printnode(Node x, int h)
   {
      for (int i = 0; i < h; i++)
         System.out.print("               ");

      System.out.println("[" + x.key + "," + x.val + "]");
   }

   void printBST()
   {
      showR( root, 0 );
   }

   public void showR(Node t, int h)
   {
      if (t == null)
         return;

      showR(t.right, h+1);
      printnode(t, h);
      showR(t.left, h+1);
   }
}