114 lines
3.1 KiB
Java
114 lines
3.1 KiB
Java
// Copyright 2011 Hakan Kjellerstrand hakank@bonetmail.com
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package com.google.ortools.samples;
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import java.io.*;
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import java.util.*;
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import java.text.*;
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import com.google.ortools.constraintsolver.DecisionBuilder;
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import com.google.ortools.constraintsolver.IntVar;
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import com.google.ortools.constraintsolver.Solver;
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import com.google.ortools.constraintsolver.*;
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public class Map2 {
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static {
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System.loadLibrary("jniortools");
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}
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/**
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*
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* Solves a simple map coloring problem, take II.
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* See http://www.hakank.org/google_or_tools/map.py
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*
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*/
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private static void solve() {
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Solver solver = new Solver("Map2");
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//
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// data
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//
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int Belgium = 0;
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int Denmark = 1;
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int France = 2;
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int Germany = 3;
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int Netherlands = 4;
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int Luxembourg = 5;
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int n = 6;
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int max_num_colors = 4;
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int[][] neighbours = {{France, Belgium},
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{France, Luxembourg},
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{France, Germany},
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{Luxembourg, Germany},
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{Luxembourg, Belgium},
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{Belgium, Netherlands},
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{Belgium, Germany},
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{Germany, Netherlands},
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{Germany, Denmark}};
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//
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// Variables
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//
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IntVar[] color = solver.makeIntVarArray(n, 1, max_num_colors, "x");
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//
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// Constraints
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//
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for(int i = 0; i < neighbours.length; i++) {
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solver.addConstraint(
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solver.makeNonEquality(color[neighbours[i][0]],
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color[neighbours[i][1]]));
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}
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// Symmetry breaking
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solver.addConstraint(solver.makeEquality(color[Belgium], 1));
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//
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// Search
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//
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DecisionBuilder db = solver.makePhase(color,
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solver.CHOOSE_FIRST_UNBOUND,
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solver.ASSIGN_MIN_VALUE);
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solver.newSearch(db);
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while (solver.nextSolution()) {
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System.out.print("Colors: ");
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for(int i = 0; i < n; i++) {
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System.out.print(color[i].value() + " ");
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}
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System.out.println();
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}
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solver.endSearch();
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// Statistics
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System.out.println();
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System.out.println("Solutions: " + solver.solutions());
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System.out.println("Failures: " + solver.failures());
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System.out.println("Branches: " + solver.branches());
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System.out.println("Wall time: " + solver.wallTime() + "ms");
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}
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public static void main(String[] args) throws Exception {
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Map2.solve();
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}
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}
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