Jip J. Dekker
1d9faf38de
git-subtree-dir: software/gecode git-subtree-split: 313e87646da4fc2752a70e83df16d993121a8e40
141 lines
4.3 KiB
C++
141 lines
4.3 KiB
C++
/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
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/*
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* Main authors:
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* Christian Schulte <schulte@gecode.org>
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*
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* Copyright:
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* Christian Schulte, 2004, 2016
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*
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* This file is part of Gecode, the generic constraint
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* development environment:
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* http://www.gecode.org
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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*/
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#ifndef GECODE_SEARCH_SEQ_LDS_HH
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#define GECODE_SEARCH_SEQ_LDS_HH
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#include <gecode/search.hh>
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#include <gecode/search/support.hh>
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#include <gecode/search/worker.hh>
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namespace Gecode { namespace Search { namespace Seq {
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/// %Probe engine for %LDS
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template<class Tracer>
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class Probe : public Worker {
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protected:
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/// Node identity type
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typedef typename Tracer::ID ID;
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/// %Node in the search tree for %LDS
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class Node {
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private:
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/// %Space of current node
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Space* _space;
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/// Choice
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const Choice* _choice;
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/// Next alternative to try
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unsigned int _alt;
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/// Node identifier
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ID _nid;
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public:
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/// Default constructor
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Node(void);
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/// Initialize with node \a s, choice \a c, and alternative \a a
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Node(Space* s, const Choice* c, unsigned int a, unsigned int nid);
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/// Return space
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Space* space(void) const;
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/// Return choice
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const Choice* choice(void) const;
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/// Return next alternative
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unsigned int alt(void) const;
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/// Return node identifier
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unsigned int nid(void) const;
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/// %Set next alternative
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void next(void);
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};
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/// Search tracer
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Tracer tracer;
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/// %Stack storing current path in search tree
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Support::DynamicStack<Node,Heap> ds;
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/// Current space
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Space* cur;
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/// Current discrepancy
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unsigned int d;
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/// Whether entire search space has been exhausted
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bool exhausted;
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public:
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/// Initialize
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Probe(const Options& opt);
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/// Initialize with space \a s
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void init(Space* s);
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/// Reset with space \a s and discrepancy \a d
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void reset(Space* s, unsigned int d);
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/// Return statistics
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Statistics statistics(void) const;
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/// Destructor
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~Probe(void);
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/// %Search for next solution
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Space* next(const Options& o);
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/// Test whether probing is done
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bool done(void) const;
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};
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/// Limited discrepancy search engine implementation
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template<class Tracer>
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class LDS : public Engine {
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protected:
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/// Search options
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Options opt;
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/// The probe engine
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Probe<Tracer> e;
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/// Root node for problem
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Space* root;
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/// Current discrepancy
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unsigned int d;
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/// Solution found for current discrepancy
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bool no_solution;
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public:
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/// Initialize for space \a s with options \a o
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LDS(Space* s, const Options& o);
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/// Return next solution (nullptr, if none exists or search has been stopped)
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virtual Space* next(void);
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/// Return statistics
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virtual Statistics statistics(void) const;
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/// Constrain future solutions to be better than \a b (should never be called)
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void constrain(const Space& b);
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/// Reset engine to restart at space \a s
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void reset(Space* s);
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/// Check whether engine has been stopped
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virtual bool stopped(void) const;
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/// Destructor
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virtual ~LDS(void);
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};
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}}}
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#include <gecode/search/seq/lds.hpp>
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#endif
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// STATISTICS: search-seq
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