permlib
0.2.6
Library for permutation computations
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00001 // --------------------------------------------------------------------------- 00002 // 00003 // This file is part of PermLib. 00004 // 00005 // Copyright (c) 2009-2011 Thomas Rehn <thomas@carmen76.de> 00006 // All rights reserved. 00007 // 00008 // Redistribution and use in source and binary forms, with or without 00009 // modification, are permitted provided that the following conditions 00010 // are met: 00011 // 1. Redistributions of source code must retain the above copyright 00012 // notice, this list of conditions and the following disclaimer. 00013 // 2. Redistributions in binary form must reproduce the above copyright 00014 // notice, this list of conditions and the following disclaimer in the 00015 // documentation and/or other materials provided with the distribution. 00016 // 3. The name of the author may not be used to endorse or promote products 00017 // derived from this software without specific prior written permission. 00018 // 00019 // THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 00020 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 00021 // OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 00022 // IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 00023 // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 00024 // NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 00025 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 00026 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 00027 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 00028 // THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 00029 // 00030 // --------------------------------------------------------------------------- 00031 00032 00033 #ifndef LEXSMALLERIMAGE_PREDICATE_H_ 00034 #define LEXSMALLERIMAGE_PREDICATE_H_ 00035 00036 #include <permlib/predicate/subgroup_predicate.h> 00037 00038 #include <set> 00039 #include <boost/foreach.hpp> 00040 #include <boost/dynamic_bitset.hpp> 00041 00042 namespace permlib { 00043 00045 00048 template <class PERM> 00049 class LexSmallerImagePredicate : public SubgroupPredicate<PERM> { 00050 public: 00052 00059 template<class ForwardIterator> 00060 LexSmallerImagePredicate(unsigned int n, ForwardIterator zerosBegin, ForwardIterator zerosEnd, ForwardIterator onesBegin, ForwardIterator onesEnd); 00061 00062 virtual bool operator()(const PERM &p) const; 00063 virtual bool childRestriction(const PERM &h, unsigned int i, unsigned long beta_i) const; 00064 virtual unsigned int limit() const; 00065 private: 00066 boost::dynamic_bitset<> m_zeros; 00067 boost::dynamic_bitset<> m_ones; 00068 unsigned long m_fixed; 00069 }; 00070 00071 // 00072 // ---- IMPLEMENTATION 00073 // 00074 00075 template <class PERM> 00076 template<class ForwardIterator> 00077 LexSmallerImagePredicate<PERM>::LexSmallerImagePredicate(unsigned int n, ForwardIterator zerosBegin, ForwardIterator zerosEnd, ForwardIterator onesBegin, ForwardIterator onesEnd) 00078 : m_zeros(n), m_ones(n), m_fixed(0) 00079 { 00080 while (zerosBegin != zerosEnd) { 00081 m_zeros.set(*zerosBegin++, 1); 00082 ++m_fixed; 00083 } 00084 while (onesBegin != onesEnd) { 00085 m_ones.set(*onesBegin++, 1); 00086 ++m_fixed; 00087 } 00088 } 00089 00090 00091 template <class PERM> 00092 bool LexSmallerImagePredicate<PERM>::operator()(const PERM &p) const { 00093 for (unsigned int i = 0; i < p.size(); ++i) { 00094 const dom_int pi = p / i; 00095 if (pi == i) 00096 continue; 00097 if (m_ones[i] && m_zeros[pi]) { 00098 PERMLIB_DEBUG( std::cout << i << " , " << pi << " !0 -> 0 TRUE" << std::endl; ) 00099 return true; 00100 } 00101 if (m_zeros[i] && !m_zeros[pi]) { 00102 PERMLIB_DEBUG( std::cout << i << " , " << pi << " 0 -> !0 FALSE" << std::endl; ) 00103 return false; 00104 } 00105 } 00106 return false; 00107 } 00108 00109 template <class PERM> 00110 bool LexSmallerImagePredicate<PERM>::childRestriction(const PERM &h, unsigned int i, unsigned long beta_i) const { 00111 // Because limit() does not depend on h, we have to check at every node 00112 // whether we have already found a element, which maps the given sets to a 00113 // lexicographically smaller set 00114 if ((*this)(h)) { 00115 PERMLIB_DEBUG( std::cout << h << " is already the desired element; TRUE" << std::endl; ) 00116 return true; 00117 } 00118 if (m_zeros[beta_i] && !m_zeros[h / beta_i]) { 00119 PERMLIB_DEBUG( std::cout << (h / beta_i) << " mapping zero " << beta_i << " to non-zero; FALSE" << std::endl; ) 00120 return false; 00121 } 00122 return true; 00123 } 00124 00125 template <class PERM> 00126 unsigned int LexSmallerImagePredicate<PERM>::limit() const { 00127 return m_fixed; 00128 } 00129 00130 } 00131 00132 #endif // -- LEXSMALLERIMAGE_PREDICATE_H_