116 lines
2.9 KiB
C#
116 lines
2.9 KiB
C#
//
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// Copyright 2012 Hakan Kjellerstrand
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//
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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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using System;
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using System.Collections;
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using System.IO;
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using System.Text.RegularExpressions;
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using Google.OrTools.ConstraintSolver;
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public class SetCovering2
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{
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/**
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*
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* Solves a set covering problem.
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* See See http://www.hakank.org/or-tools/set_covering2.py
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*
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*/
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private static void Solve()
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{
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Solver solver = new Solver("SetCovering2");
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//
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// data
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//
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// Example 9.1-2 from
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// Taha "Operations Research - An Introduction",
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// page 354ff.
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// Minimize the number of security telephones in street
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// corners on a campus.
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int n = 8; // maximum number of corners
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int num_streets = 11; // number of connected streets
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// corners of each street
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// Note: 1-based (handled below)
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int[,] corner = {{1,2},
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{2,3},
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{4,5},
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{7,8},
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{6,7},
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{2,6},
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{1,6},
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{4,7},
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{2,4},
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{5,8},
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{3,5}};
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//
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// Decision variables
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//
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IntVar[] x = solver.MakeIntVarArray(n, 0, 1, "x");
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// number of telephones, to be minimized
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IntVar z = x.Sum().Var();
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//
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// Constraints
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//
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// ensure that all streets are covered
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for(int i = 0; i < num_streets; i++) {
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solver.Add(x[corner[i,0] - 1] + x[corner[i,1] - 1] >= 1);
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}
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//
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// objective
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//
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OptimizeVar objective = z.Minimize(1);
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//
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// Search
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//
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DecisionBuilder db = solver.MakePhase(x,
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Solver.INT_VAR_DEFAULT,
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Solver.INT_VALUE_DEFAULT);
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solver.NewSearch(db, objective);
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while (solver.NextSolution()) {
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Console.WriteLine("z: {0}", z.Value());
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Console.Write("x: ");
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for(int i = 0; i < n; i++) {
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Console.Write(x[i].Value() + " ");
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}
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Console.WriteLine();
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}
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Console.WriteLine("\nSolutions: {0}", solver.Solutions());
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Console.WriteLine("WallTime: {0}ms", solver.WallTime());
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Console.WriteLine("Failures: {0}", solver.Failures());
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Console.WriteLine("Branches: {0} ", solver.Branches());
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solver.EndSearch();
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}
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public static void Main(String[] args)
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{
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Solve();
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}
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}
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