93 lines
2.7 KiB
Java
93 lines
2.7 KiB
Java
// Copyright 2011 Hakan Kjellerstrand hakank@gmail.com
|
|
// 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.
|
|
package com.google.ortools.contrib;
|
|
|
|
import com.google.ortools.Loader;
|
|
import com.google.ortools.constraintsolver.*;
|
|
import com.google.ortools.constraintsolver.DecisionBuilder;
|
|
import com.google.ortools.constraintsolver.IntVar;
|
|
import com.google.ortools.constraintsolver.Solver;
|
|
import java.io.*;
|
|
import java.text.*;
|
|
import java.util.*;
|
|
|
|
public class Map2 {
|
|
/**
|
|
* Solves a simple map coloring problem, take II. See http://www.hakank.org/google_or_tools/map.py
|
|
*/
|
|
private static void solve() {
|
|
Solver solver = new Solver("Map2");
|
|
|
|
//
|
|
// data
|
|
//
|
|
int Belgium = 0;
|
|
int Denmark = 1;
|
|
int France = 2;
|
|
int Germany = 3;
|
|
int Netherlands = 4;
|
|
int Luxembourg = 5;
|
|
|
|
int n = 6;
|
|
int max_num_colors = 4;
|
|
|
|
int[][] neighbours = {{France, Belgium}, {France, Luxembourg}, {France, Germany},
|
|
{Luxembourg, Germany}, {Luxembourg, Belgium}, {Belgium, Netherlands}, {Belgium, Germany},
|
|
{Germany, Netherlands}, {Germany, Denmark}};
|
|
|
|
//
|
|
// Variables
|
|
//
|
|
IntVar[] color = solver.makeIntVarArray(n, 1, max_num_colors, "x");
|
|
|
|
//
|
|
// Constraints
|
|
//
|
|
for (int i = 0; i < neighbours.length; i++) {
|
|
solver.addConstraint(
|
|
solver.makeNonEquality(color[neighbours[i][0]], color[neighbours[i][1]]));
|
|
}
|
|
|
|
// Symmetry breaking
|
|
solver.addConstraint(solver.makeEquality(color[Belgium], 1));
|
|
|
|
//
|
|
// Search
|
|
//
|
|
DecisionBuilder db =
|
|
solver.makePhase(color, solver.CHOOSE_FIRST_UNBOUND, solver.ASSIGN_MIN_VALUE);
|
|
solver.newSearch(db);
|
|
|
|
while (solver.nextSolution()) {
|
|
System.out.print("Colors: ");
|
|
for (int i = 0; i < n; i++) {
|
|
System.out.print(color[i].value() + " ");
|
|
}
|
|
System.out.println();
|
|
}
|
|
solver.endSearch();
|
|
|
|
// Statistics
|
|
System.out.println();
|
|
System.out.println("Solutions: " + solver.solutions());
|
|
System.out.println("Failures: " + solver.failures());
|
|
System.out.println("Branches: " + solver.branches());
|
|
System.out.println("Wall time: " + solver.wallTime() + "ms");
|
|
}
|
|
|
|
public static void main(String[] args) throws Exception {
|
|
Loader.loadNativeLibraries();
|
|
Map2.solve();
|
|
}
|
|
}
|