111 lines
2.9 KiB
C#
111 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 Langford
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{
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/**
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*
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* Langford number problem.
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* See http://www.hakank.org/or-tools/langford.py
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*
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*/
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private static void Solve(int k = 8, int num_sol = 0)
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{
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Solver solver = new Solver("Langford");
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Console.WriteLine("k: {0}", k);
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//
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// data
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//
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int p = 2 * k;
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//
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// Decision variables
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//
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IntVar[] position = solver.MakeIntVarArray(p, 0, p - 1, "position");
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IntVar[] solution = solver.MakeIntVarArray(p, 1, k, "solution");
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//
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// Constraints
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//
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solver.Add(position.AllDifferent());
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for (int i = 1; i <= k; i++)
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{
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solver.Add(position[i + k - 1] - (position[i - 1] + solver.MakeIntVar(i + 1, i + 1)) == 0);
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solver.Add(solution.Element(position[i - 1]) == i);
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solver.Add(solution.Element(position[k + i - 1]) == i);
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}
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// Symmetry breaking
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solver.Add(solution[0] < solution[2 * k - 1]);
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//
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// Search
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//
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DecisionBuilder db = solver.MakePhase(position, Solver.CHOOSE_FIRST_UNBOUND, Solver.ASSIGN_MIN_VALUE);
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solver.NewSearch(db);
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int num_solutions = 0;
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while (solver.NextSolution())
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{
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Console.Write("solution : ");
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for (int i = 0; i < p; i++)
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{
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Console.Write(solution[i].Value() + " ");
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}
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Console.WriteLine();
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num_solutions++;
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if (num_sol > 0 && num_solutions >= num_sol)
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{
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break;
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}
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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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int k = 8;
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int num_sol = 0; // 0: print all solutions
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if (args.Length > 1)
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{
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k = Convert.ToInt32(args[1]);
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}
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if (args.Length > 2)
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{
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num_sol = Convert.ToInt32(args[2]);
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}
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Solve(k, num_sol);
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}
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}
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