1 // 2 // Copyright 2012 Hakan Kjellerstrand 3 // 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // 8 // http://www.apache.org/licenses/LICENSE-2.0 9 // 10 // Unless required by applicable law or agreed to in writing, software 11 // distributed under the License is distributed on an "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 // See the License for the specific language governing permissions and 14 // limitations under the License. 15 16 using System; 17 using Google.OrTools.ConstraintSolver; 18 using System.Collections; 19 using System.Linq; 20 21 public class WhoKilledAgatha 22 { 23 /** 24 * 25 * Implements the Who killed Agatha problem. 26 * See http://www.hakank.org/google_or_tools/who_killed_agatha.py 27 * 28 */ Solve()29 private static void Solve() 30 { 31 Solver solver = new Solver("WhoKilledAgatha"); 32 33 int n = 3; 34 int agatha = 0; 35 int butler = 1; 36 int charles = 2; 37 38 // 39 // Decision variables 40 // 41 IntVar the_killer = solver.MakeIntVar(0, 2, "the_killer"); 42 IntVar the_victim = solver.MakeIntVar(0, 2, "the_victim"); 43 IntVar[,] hates = solver.MakeIntVarMatrix(n, n, 0, 1, "hates"); 44 IntVar[] hates_flat = hates.Flatten(); 45 IntVar[,] richer = solver.MakeIntVarMatrix(n, n, 0, 1, "richer"); 46 IntVar[] richer_flat = richer.Flatten(); 47 48 IntVar[] all = new IntVar[2 * n * n]; // for branching 49 for (int i = 0; i < n * n; i++) 50 { 51 all[i] = hates_flat[i]; 52 all[(n * n) + i] = richer_flat[i]; 53 } 54 55 // 56 // Constraints 57 // 58 59 // Agatha, the butler, and Charles live in Dreadsbury Mansion, and 60 // are the only ones to live there. 61 62 // A killer always hates, and is no richer than his victim. 63 // hates[the_killer, the_victim] == 1 64 // hates_flat[the_killer * n + the_victim] == 1 65 solver.Add(hates_flat.Element(the_killer * n + the_victim) == 1); 66 67 // richer[the_killer, the_victim] == 0 68 solver.Add(richer_flat.Element(the_killer * n + the_victim) == 0); 69 70 // define the concept of richer: 71 // no one is richer than him-/herself... 72 for (int i = 0; i < n; i++) 73 { 74 solver.Add(richer[i, i] == 0); 75 } 76 77 // (contd...) if i is richer than j then j is not richer than i 78 // if (i != j) => 79 // ((richer[i,j] = 1) <=> (richer[j,i] = 0)) 80 for (int i = 0; i < n; i++) 81 { 82 for (int j = 0; j < n; j++) 83 { 84 if (i != j) 85 { 86 solver.Add((richer[i, j] == 1) - (richer[j, i] == 0) == 0); 87 } 88 } 89 } 90 91 // Charles hates no one that Agatha hates. 92 // forall i in 0..2: 93 // (hates[agatha, i] = 1) => (hates[charles, i] = 0) 94 for (int i = 0; i < n; i++) 95 { 96 solver.Add((hates[agatha, i] == 1) - (hates[charles, i] == 0) <= 0); 97 } 98 99 // Agatha hates everybody except the butler. 100 solver.Add(hates[agatha, charles] == 1); 101 solver.Add(hates[agatha, agatha] == 1); 102 solver.Add(hates[agatha, butler] == 0); 103 104 // The butler hates everyone not richer than Aunt Agatha. 105 // forall i in 0..2: 106 // (richer[i, agatha] = 0) => (hates[butler, i] = 1) 107 for (int i = 0; i < n; i++) 108 { 109 solver.Add((richer[i, agatha] == 0) - (hates[butler, i] == 1) <= 0); 110 } 111 112 // The butler hates everyone whom Agatha hates. 113 // forall i : 0..2: 114 // (hates[agatha, i] = 1) => (hates[butler, i] = 1) 115 for (int i = 0; i < n; i++) 116 { 117 solver.Add((hates[agatha, i] == 1) - (hates[butler, i] == 1) <= 0); 118 } 119 120 // Noone hates everyone. 121 // forall i in 0..2: 122 // (sum j in 0..2: hates[i,j]) <= 2 123 for (int i = 0; i < n; i++) 124 { 125 solver.Add((from j in Enumerable.Range(0, n) select hates[i, j]).ToArray().Sum() <= 2); 126 } 127 128 // Who killed Agatha? 129 solver.Add(the_victim == agatha); 130 131 // 132 // Search 133 // 134 DecisionBuilder db = solver.MakePhase(all, Solver.CHOOSE_FIRST_UNBOUND, Solver.ASSIGN_MIN_VALUE); 135 136 solver.NewSearch(db); 137 138 while (solver.NextSolution()) 139 { 140 Console.WriteLine("the_killer: " + the_killer.Value()); 141 } 142 143 Console.WriteLine("\nSolutions: {0}", solver.Solutions()); 144 Console.WriteLine("WallTime: {0}ms", solver.WallTime()); 145 Console.WriteLine("Failures: {0}", solver.Failures()); 146 Console.WriteLine("Branches: {0} ", solver.Branches()); 147 148 solver.EndSearch(); 149 } 150 Main(String[] args)151 public static void Main(String[] args) 152 { 153 Solve(); 154 } 155 } 156