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]
  """Simple Travelling Salesman Problem."""
  
  # [START import]
  from __future__ import print_function
  from ortools.constraint_solver import routing_enums_pb2
  from ortools.constraint_solver import pywrapcp
  # [END import]
  
  
  # [START data_model]
  def create_data_model():
      """Stores the data for the problem."""
      data = {}
      data['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
          ],
      ]
      data['num_vehicles'] = 1
      data['depot'] = 0
      return data
      # [END data_model]
  
  
  # [START solution_printer]
  def print_solution(manager, routing, assignment):
      """Prints assignment on console."""
      print('Objective: {}'.format(assignment.ObjectiveValue()))
      index = routing.Start(0)
      plan_output = 'Route for vehicle 0:\n'
      route_distance = 0
      while not routing.IsEnd(index):
          plan_output += ' {} ->'.format(manager.IndexToNode(index))
          previous_index = index
          index = assignment.Value(routing.NextVar(index))
          route_distance += routing.GetArcCostForVehicle(previous_index, index, 0)
      plan_output += ' {}\n'.format(manager.IndexToNode(index))
      plan_output += 'Distance of the route: {}m\n'.format(route_distance)
      print(plan_output)
      # [END solution_printer]
  
  
  def main():
      """Entry point of the program."""
      # Instantiate the data problem.
      # [START data]
      data = create_data_model()
      # [END data]
  
      # Create the routing index manager.
      # [START index_manager]
      manager = pywrapcp.RoutingIndexManager(
          len(data['distance_matrix']), data['num_vehicles'], data['depot'])
      # [END index_manager]
  
      # Create Routing Model.
      # [START routing_model]
      routing = pywrapcp.RoutingModel(manager)
  
      # [END routing_model]
  
      # Create and register a transit callback.
      # [START transit_callback]
      def distance_callback(from_index, to_index):
          """Returns the distance between the two nodes."""
          # Convert from routing variable Index to distance matrix NodeIndex.
          from_node = manager.IndexToNode(from_index)
          to_node = manager.IndexToNode(to_index)
          return data['distance_matrix'][from_node][to_node]
  
      transit_callback_index = routing.RegisterTransitCallback(distance_callback)
      # [END transit_callback]
  
      # Define cost of each arc.
      # [START arc_cost]
      routing.SetArcCostEvaluatorOfAllVehicles(transit_callback_index)
      # [END arc_cost]
  
      # Setting first solution heuristic.
      # [START parameters]
      search_parameters = pywrapcp.DefaultRoutingSearchParameters()
      search_parameters.first_solution_strategy = (
          routing_enums_pb2.FirstSolutionStrategy.PATH_CHEAPEST_ARC)
      # [END parameters]
  
      # Solve the problem.
      # [START solve]
      assignment = routing.SolveWithParameters(search_parameters)
      # [END solve]
  
      # Print solution on console.
      # [START print_solution]
      if assignment:
          print_solution(manager, routing, assignment)
      # [END print_solution]
  
  
  if __name__ == '__main__':
      main()
  # [END program]
  