ortools-clone/examples/notebook/constraint_solver/simple_routing_program.ipynb

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 "cells": [
  {
   "cell_type": "markdown",
   "id": "google",
   "metadata": {},
   "source": [
    "##### Copyright 2025 Google LLC."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "apache",
   "metadata": {},
   "source": [
    "Licensed under the Apache License, Version 2.0 (the \"License\");\n",
    "you may not use this file except in compliance with the License.\n",
    "You may obtain a copy of the License at\n",
    "\n",
    "    http://www.apache.org/licenses/LICENSE-2.0\n",
    "\n",
    "Unless required by applicable law or agreed to in writing, software\n",
    "distributed under the License is distributed on an \"AS IS\" BASIS,\n",
    "WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n",
    "See the License for the specific language governing permissions and\n",
    "limitations under the License.\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "basename",
   "metadata": {},
   "source": [
    "# simple_routing_program"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "link",
   "metadata": {},
   "source": [
    "<table align=\"left\">\n",
    "<td>\n",
    "<a href=\"https://colab.research.google.com/github/google/or-tools/blob/main/examples/notebook/constraint_solver/simple_routing_program.ipynb\"><img src=\"https://raw.githubusercontent.com/google/or-tools/main/tools/colab_32px.png\"/>Run in Google Colab</a>\n",
    "</td>\n",
    "<td>\n",
    "<a href=\"https://github.com/google/or-tools/blob/main/ortools/constraint_solver/samples/simple_routing_program.py\"><img src=\"https://raw.githubusercontent.com/google/or-tools/main/tools/github_32px.png\"/>View source on GitHub</a>\n",
    "</td>\n",
    "</table>"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "doc",
   "metadata": {},
   "source": [
    "First, you must install [ortools](https://pypi.org/project/ortools/) package in this colab."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "install",
   "metadata": {},
   "outputs": [],
   "source": [
    "%pip install ortools"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "description",
   "metadata": {},
   "source": [
    "\n",
    "Vehicle Routing example.\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "code",
   "metadata": {},
   "outputs": [],
   "source": [
    "from ortools.constraint_solver import routing_enums_pb2\n",
    "from ortools.constraint_solver import pywrapcp\n",
    "\n",
    "\n",
    "\n",
    "def main():\n",
    "    \"\"\"Entry point of the program.\"\"\"\n",
    "    # Instantiate the data problem.\n",
    "    num_locations = 5\n",
    "    num_vehicles = 1\n",
    "    depot = 0\n",
    "\n",
    "    # Create the routing index manager.\n",
    "    manager = pywrapcp.RoutingIndexManager(num_locations, num_vehicles, depot)\n",
    "\n",
    "    # Create Routing Model.\n",
    "    routing = pywrapcp.RoutingModel(manager)\n",
    "\n",
    "    # Create and register a transit callback.\n",
    "    def distance_callback(from_index, to_index):\n",
    "        \"\"\"Returns the absolute difference between the two nodes.\"\"\"\n",
    "        # Convert from routing variable Index to user NodeIndex.\n",
    "        from_node = int(manager.IndexToNode(from_index))\n",
    "        to_node = int(manager.IndexToNode(to_index))\n",
    "        return abs(to_node - from_node)\n",
    "\n",
    "    transit_callback_index = routing.RegisterTransitCallback(distance_callback)\n",
    "\n",
    "    # Define cost of each arc.\n",
    "    routing.SetArcCostEvaluatorOfAllVehicles(transit_callback_index)\n",
    "\n",
    "    # Setting first solution heuristic.\n",
    "    search_parameters = pywrapcp.DefaultRoutingSearchParameters()\n",
    "    search_parameters.first_solution_strategy = (\n",
    "        routing_enums_pb2.FirstSolutionStrategy.PATH_CHEAPEST_ARC\n",
    "    )  # pylint: disable=no-member\n",
    "\n",
    "    # Solve the problem.\n",
    "    assignment = routing.SolveWithParameters(search_parameters)\n",
    "\n",
    "    # Print solution on console.\n",
    "    print(f\"Objective: {assignment.ObjectiveValue()}\")\n",
    "    index = routing.Start(0)\n",
    "    plan_output = \"Route for vehicle 0:\\n\"\n",
    "    route_distance = 0\n",
    "    while not routing.IsEnd(index):\n",
    "        plan_output += f\"{manager.IndexToNode(index)} -> \"\n",
    "        previous_index = index\n",
    "        index = assignment.Value(routing.NextVar(index))\n",
    "        route_distance += routing.GetArcCostForVehicle(previous_index, index, 0)\n",
    "    plan_output += f\"{manager.IndexToNode(index)}\\n\"\n",
    "    plan_output += f\"Distance of the route: {route_distance}m\\n\"\n",
    "    print(plan_output)\n",
    "\n",
    "\n",
    "main()\n",
    "\n"
   ]
  }
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