text: // Copyright 2010-2018 Google LLC
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //     http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  // [START program]
  // [START import]
  #include <cstdint>
  #include <vector>
  
  #include "ortools/constraint_solver/routing.h"
  #include "ortools/constraint_solver/routing_enums.pb.h"
  #include "ortools/constraint_solver/routing_index_manager.h"
  #include "ortools/constraint_solver/routing_parameters.h"
  // [END import]
  
  namespace operations_research {
  // [START data_model]
  struct DataModel {
    const std::vector<std::vector<int64_t>> distance_matrix{
        {0, 548, 776, 696, 582, 274, 502, 194, 308, 194, 536, 502, 388, 354, 468,
         776, 662},
        {548, 0, 684, 308, 194, 502, 730, 354, 696, 742, 1084, 594, 480, 674,
         1016, 868, 1210},
        {776, 684, 0, 992, 878, 502, 274, 810, 468, 742, 400, 1278, 1164, 1130,
         788, 1552, 754},
        {696, 308, 992, 0, 114, 650, 878, 502, 844, 890, 1232, 514, 628, 822,
         1164, 560, 1358},
        {582, 194, 878, 114, 0, 536, 764, 388, 730, 776, 1118, 400, 514, 708,
         1050, 674, 1244},
        {274, 502, 502, 650, 536, 0, 228, 308, 194, 240, 582, 776, 662, 628, 514,
         1050, 708},
        {502, 730, 274, 878, 764, 228, 0, 536, 194, 468, 354, 1004, 890, 856, 514,
         1278, 480},
        {194, 354, 810, 502, 388, 308, 536, 0, 342, 388, 730, 468, 354, 320, 662,
         742, 856},
        {308, 696, 468, 844, 730, 194, 194, 342, 0, 274, 388, 810, 696, 662, 320,
         1084, 514},
        {194, 742, 742, 890, 776, 240, 468, 388, 274, 0, 342, 536, 422, 388, 274,
         810, 468},
        {536, 1084, 400, 1232, 1118, 582, 354, 730, 388, 342, 0, 878, 764, 730,
         388, 1152, 354},
        {502, 594, 1278, 514, 400, 776, 1004, 468, 810, 536, 878, 0, 114, 308,
         650, 274, 844},
        {388, 480, 1164, 628, 514, 662, 890, 354, 696, 422, 764, 114, 0, 194, 536,
         388, 730},
        {354, 674, 1130, 822, 708, 628, 856, 320, 662, 388, 730, 308, 194, 0, 342,
         422, 536},
        {468, 1016, 788, 1164, 1050, 514, 514, 662, 320, 274, 388, 650, 536, 342,
         0, 764, 194},
        {776, 868, 1552, 560, 674, 1050, 1278, 742, 1084, 810, 1152, 274, 388,
         422, 764, 0, 798},
        {662, 1210, 754, 1358, 1244, 708, 480, 856, 514, 468, 354, 844, 730, 536,
         194, 798, 0},
    };
    const int num_vehicles = 4;
    const RoutingIndexManager::NodeIndex depot{0};
  };
  // [END data_model]
  
  //! @brief Print the solution.
  //! @param[in] data Data of the problem.
  //! @param[in] manager Index manager used.
  //! @param[in] routing Routing solver used.
  //! @param[in] solution Solution found by the solver.
  // [START solution_printer]
  void PrintSolution(const DataModel& data, const RoutingIndexManager& manager,
                     const RoutingModel& routing, const Assignment& solution) {
    int64_t max_route_distance{0};
    for (int vehicle_id = 0; vehicle_id < data.num_vehicles; ++vehicle_id) {
      int64_t index = routing.Start(vehicle_id);
      LOG(INFO) << "Route for Vehicle " << vehicle_id << ":";
      int64_t route_distance{0};
      std::stringstream route;
      while (routing.IsEnd(index) == false) {
        route << manager.IndexToNode(index).value() << " -> ";
        int64_t previous_index = index;
        index = solution.Value(routing.NextVar(index));
        route_distance += routing.GetArcCostForVehicle(previous_index, index,
                                                       int64_t{vehicle_id});
      }
      LOG(INFO) << route.str() << manager.IndexToNode(index).value();
      LOG(INFO) << "Distance of the route: " << route_distance << "m";
      max_route_distance = std::max(route_distance, max_route_distance);
    }
    LOG(INFO) << "Maximum of the route distances: " << max_route_distance << "m";
    LOG(INFO) << "";
    LOG(INFO) << "Problem solved in " << routing.solver()->wall_time() << "ms";
  }
  // [END solution_printer]
  
  void VrpGlobalSpan() {
    // Instantiate the data problem.
    // [START data]
    DataModel data;
    // [END data]
  
    // Create Routing Index Manager
    // [START index_manager]
    RoutingIndexManager manager(data.distance_matrix.size(), data.num_vehicles,
                                data.depot);
    // [END index_manager]
  
    // Create Routing Model.
    // [START routing_model]
    RoutingModel routing(manager);
    // [END routing_model]
  
    // Create and register a transit callback.
    // [START transit_callback]
    const int transit_callback_index = routing.RegisterTransitCallback(
        [&data, &manager](int64 from_index, int64 to_index) -> int64 {
          // Convert from routing variable Index to distance matrix NodeIndex.
          auto from_node = manager.IndexToNode(from_index).value();
          auto to_node = manager.IndexToNode(to_index).value();
          return data.distance_matrix[from_node][to_node];
        });
    // [END transit_callback]
  
    // Define cost of each arc.
    // [START arc_cost]
    routing.SetArcCostEvaluatorOfAllVehicles(transit_callback_index);
    // [END arc_cost]
  
    // Add Distance constraint.
    // [START distance_constraint]
    routing.AddDimension(transit_callback_index, 0, 3000,
                         true,  // start cumul to zero
                         "Distance");
    routing.GetMutableDimension("Distance")->SetGlobalSpanCostCoefficient(100);
    // [END distance_constraint]
  
    // Setting first solution heuristic.
    // [START parameters]
    RoutingSearchParameters searchParameters = DefaultRoutingSearchParameters();
    searchParameters.set_first_solution_strategy(
        FirstSolutionStrategy::PATH_CHEAPEST_ARC);
    // [END parameters]
  
    // Solve the problem.
    // [START solve]
    const Assignment* solution = routing.SolveWithParameters(searchParameters);
    // [END solve]
  
    // Print solution on console.
    // [START print_solution]
    PrintSolution(data, manager, routing, *solution);
    // [END print_solution]
  }
  }  // namespace operations_research
  
  int main(int argc, char** argv) {
    operations_research::VrpGlobalSpan();
    return EXIT_SUCCESS;
  }
  // [END program]
  