if num_locations > 0:
    routing = pywrapcp.RoutingModel(num_locations, 1, 0)
    search_parameters = pywrapcp.RoutingModel.DefaultSearchParameters()

    dist_between_locations = CreateDistanceCallback()
    dist_callback = dist_between_locations.Distance
    routing.SetArcCostEvaluatorOfAllVehicles(dist_callback)

    total_times = CreateTotalTimeCallback()
    total_time_callback = total_times.TotalTime
    routing.AddDimension(total_time_callback,
                         24 * 3600,
                         24 * 3600,
                         true,
                         "Time")

    time_dimension = routing.GetDimensionOrDie(time)
    for location in range(1, num_locations):
        start = DataHolder.times[location]
        end = DataHolder.times[location] + ( 3 * 3600 )
        time_dimension.CumulVar(location).SetRange(start, end)