After you finish creating the RoutingModel and RoutingSolver classes and the printInformation function, you use them in the main function. You can use command line syntax to pass the names of input files to the model. If you do not specify input files, the defaults will be used. In the main function, you first create an environment. Then you create an instance of the RoutingModel class, which takes the environment and input files as parameters. You create an instance of the RoutingSolver class, which takes the model as a parameter. You call the member function RoutingSolver::insertAllReturnVisits to add the return visits to the first solution. You call the member function RoutingSolver::orderVisits to create a submodel and order the customer visits. This member function takes two parameters: the unordered visit array and the graph from the routing model mdl. You call the member function RoutingSolver::insertCustomerVisits to insert the ordered customer visits into the first solution. You use Solver to improve the first solution and print this solution. The following code is provided for you:

int main(int argc, char * argv[]) {
  IloEnv env;
  try {
    RoutingModel mdl(env, argc, argv);
    RoutingSolver solver(mdl);
    solver.insertAllReturnVisits();
    solver.orderVisits(mdl.getUnorderedVisitArray(), mdl.getGraph());
    if (solver.insertCustomerVisits()) {
      solver.improveWithNhood();
      solver.printInformation("***Solution after improvements with nhood***");
    }
  } catch(IloException& ex) {
    cerr << "Error: " << ex << endl;
  }
  env.end();
  return 0;
}