public static void TestOneInstance(string file, ITasker xr, byte nrThreads, int nrSeconds)
{
    // Read instance and do the fleet routing
    FleetRouter rout = Instance.Read(file);
    FleetResult res = rout.Solve(nrSeconds);

    // Generate result string
    string strRes = "Result: " + res.TotalCost + "  Vehicles: " + res.NrRoutes + Environment.NewLine;
    for (int i = 0; i < res.NrRoutes; i++)
    {
        strRes += "Route " + (i + 1) + ": ";
        for (int j = 0; j < res.Routes[i].NrNodes; j++)
            strRes += res.Routes[i].Nodes[j].Index + " ";
        strRes += Environment.NewLine;
    }
    MessageBox.Show(strRes);
}