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# 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]
"""Vehicle Routing example."""

# [START import]
from __future__ import print_function
from ortools.constraint_solver import routing_enums_pb2
from ortools.constraint_solver import pywrapcp
from ortools.constraint_solver import pywrapcp
# [END import]


"""Entry point of the program."""
# Instantiate the data problem.
# [START data]
num_locations = 5
num_vehicles = 1
depot = 0
# [END data]

# Create the routing index manager.
# [START index_manager]
manager = pywrapcp.RoutingIndexManager(num_locations, num_vehicles, 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 absolute difference between the two nodes."""
    # Convert from routing variable Index to user NodeIndex.
    from_node = int(manager.IndexToNode(from_index))
    to_node = int(manager.IndexToNode(to_index))
    return abs(to_node - from_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)  # pylint: disable=no-member
# [END parameters]

# Solve the problem.
# [START solve]
assignment = routing.SolveWithParameters(search_parameters)
# [END solve]

# Print solution on console.
# [START print_solution]
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 print_solution]