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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, 2016
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#ifndef GECODE_SEARCH_RELAX_HH
35#define GECODE_SEARCH_RELAX_HH
36
37#include <gecode/kernel.hh>
38#include <gecode/search.hh>
39
40namespace Gecode { namespace Search {
41
42 /// Relax variables in \a x from solution \a sx with probability \a p
43 template<class VarArgs, class Post>
44 forceinline void
45 relax(Home home, const VarArgs& x, const VarArgs& sx, Rnd r,
46 double p, Post& post);
47
48
49 template<class VarArgs, class Post>
50 forceinline void
51 relax(Home home, const VarArgs& x, const VarArgs& sx, Rnd r,
52 double p, Post& post) {
53 if (home.failed())
54 return;
55 Region reg;
56 // Which variables to assign
57 Support::BitSet<Region> ax(reg, static_cast<unsigned int>(x.size()));
58 // Select randomly with probability p to relax value
59 for (int i=0; i<x.size(); i++)
60 if (r(UINT_MAX) >=
61 static_cast<unsigned int>(p * static_cast<double>(UINT_MAX)))
62 ax.set(static_cast<unsigned int>(i));
63 if (ax.all())
64 // Choose one variable uniformly and unset it
65 ax.clear(r(static_cast<unsigned int>(x.size())));
66 for (Iter::Values::BitSet<Support::BitSet<Region> > i(ax); i(); ++i)
67 if (post(home, x[i.val()], sx[i.val()]) != ES_OK) {
68 home.failed();
69 return;
70 }
71 }
72
73}}
74
75#endif
76
77// STATISTICS: search-other