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dekker.one
1/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
2/*
3 * Main authors:
4 * Guido Tack <tack@gecode.org>
5 *
6 * Copyright:
7 * Guido Tack, 2004
8 *
9 * This file is part of Gecode, the generic constraint
10 * development environment:
11 * http://www.gecode.org
12 *
13 * Permission is hereby granted, free of charge, to any person obtaining
14 * a copy of this software and associated documentation files (the
15 * "Software"), to deal in the Software without restriction, including
16 * without limitation the rights to use, copy, modify, merge, publish,
17 * distribute, sublicense, and/or sell copies of the Software, and to
18 * permit persons to whom the Software is furnished to do so, subject to
19 * the following conditions:
20 *
21 * The above copyright notice and this permission notice shall be
22 * included in all copies or substantial portions of the Software.
23 *
24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
28 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
29 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
30 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
31 *
32 */
33
34#include <gecode/driver.hh>
35#include <gecode/int.hh>
36#include <gecode/set.hh>
37
38using namespace Gecode;
39
40/**
41 * \brief %Example: %Steiner triples
42 *
43 * See also problem 044 at http://www.csplib.org/.
44 *
45 * \ingroup Example
46 *
47 */
48class Steiner : public Script {
49public:
50 /// Model variants
51 enum {
52 MODEL_NONE, ///< Use simple relation constraint
53 MODEL_MATCHING, ///< Use matching constraints
54 MODEL_SEQ ///< Use sequence constraints
55 };
56 /// Order of the Steiner problem
57 int n;
58 /// Number of Steiner triples
59 int noOfTriples;
60
61 /// The steiner triples
62 SetVarArray triples;
63
64 /// Actual model
65 Steiner(const SizeOptions& opt)
66 : Script(opt), n(opt.size()), noOfTriples((n*(n-1))/6),
67 triples(*this, noOfTriples, IntSet::empty, 1, n, 3U, 3U) {
68
69 for (int i=0; i<noOfTriples; i++) {
70 for (int j=i+1; j<noOfTriples; j++) {
71 SetVar x = triples[i];
72 SetVar y = triples[j];
73
74 SetVar atmostOne(*this,IntSet::empty,1,n,0U,1U);
75 rel(*this, (x & y) == atmostOne);
76
77 IntVar x1(*this,1,n);
78 IntVar x2(*this,1,n);
79 IntVar x3(*this,1,n);
80 IntVar y1(*this,1,n);
81 IntVar y2(*this,1,n);
82 IntVar y3(*this,1,n);
83
84 if (opt.model() == MODEL_NONE) {
85 /* Naive alternative:
86 * just including the ints in the set
87 */
88 rel(*this, singleton(x1) <= x);
89 rel(*this, singleton(x2) <= x);
90 rel(*this, singleton(x3) <= x);
91 rel(*this, singleton(y1) <= y);
92 rel(*this, singleton(y2) <= y);
93 rel(*this, singleton(y3) <= y);
94
95 } else if (opt.model() == MODEL_MATCHING) {
96 /* Smart alternative:
97 * Using matching constraints
98 */
99
100 channelSorted(*this, {x1,x2,x3}, x);
101 channelSorted(*this, {y1,y2,y3}, y);
102 } else if (opt.model() == MODEL_SEQ) {
103 SetVar sx1 = expr(*this, singleton(x1));
104 SetVar sx2 = expr(*this, singleton(x2));
105 SetVar sx3 = expr(*this, singleton(x3));
106 SetVar sy1 = expr(*this, singleton(y1));
107 SetVar sy2 = expr(*this, singleton(y2));
108 SetVar sy3 = expr(*this, singleton(y3));
109 sequence(*this,{sx1,sx2,sx3},x);
110 sequence(*this,{sy1,sy2,sy3},y);
111 }
112
113 /* Breaking symmetries */
114 rel(*this, x1 < x2);
115 rel(*this, x2 < x3);
116 rel(*this, x1 < x3);
117
118 rel(*this, y1 < y2);
119 rel(*this, y2 < y3);
120 rel(*this, y1 < y3);
121
122 linear(*this,
123 {(n+1)*(n+1), n+1, 1, -(n+1)*(n+1), -(n+1), -1},
124 {x1, x2, x3, y1, y2, y3},
125 IRT_LE, 0);
126 }
127 }
128
129 branch(*this, triples, SET_VAR_NONE(), SET_VAL_MIN_INC());
130 }
131 /// Print solution
132 virtual void
133 print(std::ostream& os) const {
134 for (int i=0; i<noOfTriples; i++) {
135 os << "\t[" << i << "] = " << triples[i] << std::endl;
136 }
137 }
138 /// Constructor for copying \a s
139 Steiner(Steiner& s) : Script(s), n(s.n), noOfTriples(s.noOfTriples) {
140 triples.update(*this, s.triples);
141 }
142 /// Copy during cloning
143 virtual Space*
144 copy(void) {
145 return new Steiner(*this);
146 }
147};
148
149/** \brief Main-function
150 * \relates Steiner
151 */
152int
153main(int argc, char* argv[]) {
154 SizeOptions opt("Steiner");
155 opt.model(Steiner::MODEL_NONE);
156 opt.model(Steiner::MODEL_NONE, "rel", "Use simple relation constraints");
157 opt.model(Steiner::MODEL_MATCHING, "matching", "Use matching constraints");
158 opt.model(Steiner::MODEL_SEQ, "sequence", "Use sequence constraints");
159 opt.size(9);
160 opt.iterations(20);
161 opt.parse(argc,argv);
162 Script::run<Steiner,DFS,SizeOptions>(opt);
163 return 0;
164}
165
166
167// STATISTICS: example-any
168