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dekker.one
1/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
2/*
3 * Main authors:
4 * Christian Schulte <schulte@gecode.org>
5 *
6 * Copyright:
7 * Christian Schulte, 2001
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/minimodel.hh>
37
38using namespace Gecode;
39
40/**
41 * \brief %Example: Magic squares
42 *
43 * Compute magic squares of arbitrary size
44 *
45 * See problem 19 at http://www.csplib.org/.
46 *
47 * \ingroup Example
48 *
49 */
50class MagicSquare : public Script {
51private:
52 /// Size of magic square
53 const int n;
54 /// Fields of square
55 IntVarArray x;
56
57public:
58 /// Branching to use for model
59 enum {
60 BRANCH_SIZE, ///< Branch by size
61 BRANCH_AFC_SIZE ///< Branch by size over AFC
62 };
63 /// Post constraints
64 MagicSquare(const SizeOptions& opt)
65 : Script(opt), n(opt.size()), x(*this,n*n,1,n*n) {
66 // Number of fields on square
67 const int nn = n*n;
68
69 // Sum of all a row, column, or diagonal
70 const int s = nn*(nn+1) / (2*n);
71
72 // Matrix-wrapper for the square
73 Matrix<IntVarArray> m(x, n, n);
74
75 for (int i = n; i--; ) {
76 linear(*this, m.row(i), IRT_EQ, s, opt.ipl());
77 linear(*this, m.col(i), IRT_EQ, s, opt.ipl());
78 }
79 // Both diagonals must have sum s
80 {
81 IntVarArgs d1y(n);
82 IntVarArgs d2y(n);
83 for (int i = n; i--; ) {
84 d1y[i] = m(i,i);
85 d2y[i] = m(n-i-1,i);
86 }
87 linear(*this, d1y, IRT_EQ, s, opt.ipl());
88 linear(*this, d2y, IRT_EQ, s, opt.ipl());
89 }
90
91 // All fields must be distinct
92 distinct(*this, x, opt.ipl());
93
94 // Break some (few) symmetries
95 rel(*this, m(0,0), IRT_GR, m(0,n-1));
96 rel(*this, m(0,0), IRT_GR, m(n-1,0));
97
98 switch (opt.branching()) {
99 case BRANCH_SIZE:
100 branch(*this, x, INT_VAR_SIZE_MIN(), INT_VAL_SPLIT_MIN());
101 break;
102 case BRANCH_AFC_SIZE:
103 branch(*this, x, INT_VAR_AFC_SIZE_MAX(opt.decay()), INT_VAL_SPLIT_MIN());
104 break;
105 }
106 }
107
108 /// Constructor for cloning \a s
109 MagicSquare(MagicSquare& s) : Script(s), n(s.n) {
110 x.update(*this, s.x);
111 }
112
113 /// Copy during cloning
114 virtual Space*
115 copy(void) {
116 return new MagicSquare(*this);
117 }
118 /// Print solution
119 virtual void
120 print(std::ostream& os) const {
121 // Matrix-wrapper for the square
122 Matrix<IntVarArray> m(x, n, n);
123 for (int i = 0; i<n; i++) {
124 os << "\t";
125 for (int j = 0; j<n; j++) {
126 os.width(2);
127 os << m(i,j) << " ";
128 }
129 os << std::endl;
130 }
131 }
132
133};
134
135/** \brief Main-function
136 * \relates MagicSquare
137 */
138int
139main(int argc, char* argv[]) {
140 SizeOptions opt("MagicSquare");
141 opt.iterations(1);
142 opt.size(7);
143 opt.branching(MagicSquare::BRANCH_SIZE);
144 opt.branching(MagicSquare::BRANCH_SIZE, "size");
145 opt.branching(MagicSquare::BRANCH_AFC_SIZE, "afc-size");
146 opt.parse(argc,argv);
147 Script::run<MagicSquare,DFS,SizeOptions>(opt);
148 return 0;
149}
150
151// STATISTICS: example-any
152