// Chap 6, p 293

boolean IsPath(int OriginCity, int DestCity, mapClass M)
// recursive version
{
   int     NextCity;
   boolean Success, Done;

   // mark the current city as visited
   M.MarkVisited(OriginCity);

   // base case: the destination is reached
   if (OriginCity == DestCity)
      return TRUE;

   else  // try a flight to each unvisited city
   {  Done = FALSE;
      M.GetNextCity(OriginCity, NextCity, Success);

      while (Success && !Done)
	 Done = IsPath(NextCity, DestCity, M);
      return Done;
   }  // end if
}  // end IsPath