123 lines
2.9 KiB
C#
123 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.Linq;
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using System.Text.RegularExpressions;
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using Google.OrTools.ConstraintSolver;
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public class CuriousSetOfIntegers
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{
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public static void Decreasing(Solver solver, IntVar[] x) {
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for(int i = 0; i < x.Length - 1; i++) {
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solver.Add(x[i] <= x[i+1]);
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}
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}
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/**
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*
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* Crypto problem in Google CP Solver.
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*
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* Martin Gardner (February 1967):
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* """
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* The integers 1,3,8, and 120 form a set with a remarkable property: the
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* product of any two integers is one less than a perfect square. Find
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* a fifth number that can be added to the set without destroying
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* this property.
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* """
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*
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* Also see, http://www.hakank.org/or-tools/curious_set_of_integers.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("CuriousSetOfIntegers");
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//
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// data
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//
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int n = 5;
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int max_val = 10000;
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//
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// Decision variables
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//
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IntVar[] x = solver.MakeIntVarArray(n, 0, max_val, "x");
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//
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// Constraints
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//
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solver.Add(x.AllDifferent());
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for(int i = 0; i < n - 1; i++) {
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for(int j = i + 1; j < n; j++) {
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IntVar p = solver.MakeIntVar(0, max_val);
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solver.Add((p.Square() - 1) - (x[i] * x[j]) == 0);
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}
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}
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// Symmetry breaking
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Decreasing(solver, x);
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// This is the original problem
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// Which is the fifth number?
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int[] v = {1,3,8,120};
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IntVar[] b = (from i in Enumerable.Range(0, n)
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select x[i].IsMember(v)).ToArray();
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solver.Add(b.Sum() == 4);
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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.CHOOSE_MIN_SIZE_LOWEST_MIN,
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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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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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