133 lines
5.0 KiB
Java
133 lines
5.0 KiB
Java
// Copyright 2010-2025 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]
|
|
package com.google.ortools.constraintsolver.samples;
|
|
|
|
// [START import]
|
|
import com.google.ortools.Loader;
|
|
import com.google.ortools.constraintsolver.Assignment;
|
|
import com.google.ortools.constraintsolver.FirstSolutionStrategy;
|
|
import com.google.ortools.constraintsolver.RoutingIndexManager;
|
|
import com.google.ortools.constraintsolver.RoutingModel;
|
|
import com.google.ortools.constraintsolver.RoutingSearchParameters;
|
|
import com.google.ortools.constraintsolver.main;
|
|
import java.util.logging.Logger;
|
|
|
|
// [END import]
|
|
|
|
/** Minimal TSP using distance matrix. */
|
|
public class TspCities {
|
|
private static final Logger logger = Logger.getLogger(TspCities.class.getName());
|
|
|
|
// [START data_model]
|
|
static class DataModel {
|
|
public final long[][] distanceMatrix = {
|
|
{0, 2451, 713, 1018, 1631, 1374, 2408, 213, 2571, 875, 1420, 2145, 1972},
|
|
{2451, 0, 1745, 1524, 831, 1240, 959, 2596, 403, 1589, 1374, 357, 579},
|
|
{713, 1745, 0, 355, 920, 803, 1737, 851, 1858, 262, 940, 1453, 1260},
|
|
{1018, 1524, 355, 0, 700, 862, 1395, 1123, 1584, 466, 1056, 1280, 987},
|
|
{1631, 831, 920, 700, 0, 663, 1021, 1769, 949, 796, 879, 586, 371},
|
|
{1374, 1240, 803, 862, 663, 0, 1681, 1551, 1765, 547, 225, 887, 999},
|
|
{2408, 959, 1737, 1395, 1021, 1681, 0, 2493, 678, 1724, 1891, 1114, 701},
|
|
{213, 2596, 851, 1123, 1769, 1551, 2493, 0, 2699, 1038, 1605, 2300, 2099},
|
|
{2571, 403, 1858, 1584, 949, 1765, 678, 2699, 0, 1744, 1645, 653, 600},
|
|
{875, 1589, 262, 466, 796, 547, 1724, 1038, 1744, 0, 679, 1272, 1162},
|
|
{1420, 1374, 940, 1056, 879, 225, 1891, 1605, 1645, 679, 0, 1017, 1200},
|
|
{2145, 357, 1453, 1280, 586, 887, 1114, 2300, 653, 1272, 1017, 0, 504},
|
|
{1972, 579, 1260, 987, 371, 999, 701, 2099, 600, 1162, 1200, 504, 0},
|
|
};
|
|
public final int vehicleNumber = 1;
|
|
public final int depot = 0;
|
|
}
|
|
// [END data_model]
|
|
|
|
// [START solution_printer]
|
|
/// @brief Print the solution.
|
|
static void printSolution(
|
|
RoutingModel routing, RoutingIndexManager manager, Assignment solution) {
|
|
// Solution cost.
|
|
logger.info("Objective: " + solution.objectiveValue() + "miles");
|
|
// Inspect solution.
|
|
logger.info("Route:");
|
|
long routeDistance = 0;
|
|
String route = "";
|
|
long index = routing.start(0);
|
|
while (!routing.isEnd(index)) {
|
|
route += manager.indexToNode(index) + " -> ";
|
|
long previousIndex = index;
|
|
index = solution.value(routing.nextVar(index));
|
|
routeDistance += routing.getArcCostForVehicle(previousIndex, index, 0);
|
|
}
|
|
route += manager.indexToNode(routing.end(0));
|
|
logger.info(route);
|
|
logger.info("Route distance: " + routeDistance + "miles");
|
|
}
|
|
// [END solution_printer]
|
|
|
|
public static void main(String[] args) throws Exception {
|
|
Loader.loadNativeLibraries();
|
|
// Instantiate the data problem.
|
|
// [START data]
|
|
final DataModel data = new DataModel();
|
|
// [END data]
|
|
|
|
// Create Routing Index Manager
|
|
// [START index_manager]
|
|
RoutingIndexManager manager =
|
|
new RoutingIndexManager(data.distanceMatrix.length, data.vehicleNumber, data.depot);
|
|
// [END index_manager]
|
|
|
|
// Create Routing Model.
|
|
// [START routing_model]
|
|
RoutingModel routing = new RoutingModel(manager);
|
|
// [END routing_model]
|
|
|
|
// Create and register a transit callback.
|
|
// [START transit_callback]
|
|
final int transitCallbackIndex =
|
|
routing.registerTransitCallback((long fromIndex, long toIndex) -> {
|
|
// Convert from routing variable Index to user NodeIndex.
|
|
int fromNode = manager.indexToNode(fromIndex);
|
|
int toNode = manager.indexToNode(toIndex);
|
|
return data.distanceMatrix[fromNode][toNode];
|
|
});
|
|
// [END transit_callback]
|
|
|
|
// Define cost of each arc.
|
|
// [START arc_cost]
|
|
routing.setArcCostEvaluatorOfAllVehicles(transitCallbackIndex);
|
|
// [END arc_cost]
|
|
|
|
// Setting first solution heuristic.
|
|
// [START parameters]
|
|
RoutingSearchParameters searchParameters =
|
|
main.defaultRoutingSearchParameters()
|
|
.toBuilder()
|
|
.setFirstSolutionStrategy(FirstSolutionStrategy.Value.PATH_CHEAPEST_ARC)
|
|
.build();
|
|
// [END parameters]
|
|
|
|
// Solve the problem.
|
|
// [START solve]
|
|
Assignment solution = routing.solveWithParameters(searchParameters);
|
|
// [END solve]
|
|
|
|
// Print solution on console.
|
|
// [START print_solution]
|
|
printSolution(routing, manager, solution);
|
|
// [END print_solution]
|
|
}
|
|
}
|
|
// [END program]
|