class List
{
   int key;
   int value;
   List next;
}

public class Lookup
{
   public static void main(String[] args)
   {
      if ( args.length < 1 )
      {
         System.out.println("Usage: java Lookup  KEY\n");
	 System.exit(1);
      }

      List head = makeList();

      System.out.print("List: ");
      Print( head );

      int searchKey = Integer.parseInt( args[0] );

      System.out.println("Look up: " + searchKey);

      int searchValue = Lookup( head, searchKey);

      System.out.println("Returned value = " + searchValue);
   }

   /* =============================================
      Recursive look up function
      ============================================= */
   static int  Lookup( List h, int searchKey )
   {
      if ( h == null )
         return 0;             // Not found is represented by 0     
      else if ( h.key == searchKey )
         return (h.value);
      else 
         return Lookup( h.next, searchKey );
   }


   // Help function: print list
   public static void Print(List head)
   {
      while (head != null)
      { 
          System.out.print("[" + head.key + "," + head.value + "]");
          head = head.next;

	  if ( head != null )
             System.out.print("->");

      }
      System.out.println();
   }

   // Help function: make the list in teaching notes
   public static List makeList()
   {
      int[] key = {111, 222, 333, 444, 555};
      int[] value = {58, 67, 34, 87, 98};
      List h = null;
      List p;

      for (int i = key.length-1; i >= 0; i-- )
      {
         p = new List( );
         p.key = key[i];
         p.value = value[i];

	 p.next = h;
	 h = p;
      }

      return h;
   }

}