Jip J. Dekker
1d9faf38de
git-subtree-dir: software/gecode git-subtree-split: 313e87646da4fc2752a70e83df16d993121a8e40
352 lines
9.0 KiB
C++
352 lines
9.0 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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namespace Gecode { namespace Search { namespace Seq {
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/*
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* Nodes for the probing engine (just remember next alternative
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* to try)
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*
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*/
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template<class Tracer>
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forceinline
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Probe<Tracer>::Node::Node(void) {}
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template<class Tracer>
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forceinline
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Probe<Tracer>::Node::Node(Space* s, const Choice* c, unsigned int a,
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unsigned int nid)
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: _space(s), _choice(c), _alt(a), _nid(nid) {}
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template<class Tracer>
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forceinline Space*
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Probe<Tracer>::Node::space(void) const {
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return _space;
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}
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template<class Tracer>
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forceinline const Choice*
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Probe<Tracer>::Node::choice(void) const {
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return _choice;
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}
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template<class Tracer>
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forceinline unsigned int
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Probe<Tracer>::Node::alt(void) const {
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return _alt;
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}
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template<class Tracer>
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forceinline unsigned int
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Probe<Tracer>::Node::nid(void) const {
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return _nid;
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}
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template<class Tracer>
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forceinline void
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Probe<Tracer>::Node::next(void) {
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_alt--;
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}
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/*
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* The probing engine: computes all solutions with
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* exact number of discrepancies (solutions with
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* fewer discrepancies are discarded)
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*
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*/
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template<class Tracer>
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forceinline
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Probe<Tracer>::Probe(const Options& opt)
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: tracer(opt.tracer), ds(heap) {
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tracer.engine(SearchTracer::EngineType::LDS, 1U);
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tracer.worker();
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}
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template<class Tracer>
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forceinline void
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Probe<Tracer>::init(Space* s) {
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cur = s; d = 0U; exhausted = true;
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if (tracer)
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tracer.ei()->invalidate();
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}
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template<class Tracer>
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forceinline void
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Probe<Tracer>::reset(Space* s, unsigned int d0) {
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tracer.round();
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delete cur;
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while (!ds.empty())
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delete ds.pop().space();
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cur = s; d = d0; exhausted = true;
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if (tracer)
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tracer.ei()->invalidate();
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Worker::reset(0);
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}
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template<class Tracer>
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forceinline Statistics
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Probe<Tracer>::statistics(void) const {
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return *this;
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}
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template<class Tracer>
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forceinline bool
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Probe<Tracer>::done(void) const {
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return exhausted;
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}
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template<class Tracer>
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forceinline
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Probe<Tracer>::~Probe(void) {
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tracer.done();
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delete cur;
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while (!ds.empty())
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delete ds.pop().space();
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}
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template<class Tracer>
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forceinline Space*
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Probe<Tracer>::next(const Options& opt) {
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start();
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while (true) {
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if (cur == nullptr) {
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backtrack:
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if (ds.empty())
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return nullptr;
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if (stop(opt))
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return nullptr;
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unsigned int a = ds.top().alt();
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const Choice* ch = ds.top().choice();
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unsigned int nid = ds.top().nid();
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if (a == 0) {
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cur = ds.pop().space();
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if (tracer)
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tracer.ei()->init(tracer.wid(), nid, 0, *cur, *ch);
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cur->commit(*ch,0);
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delete ch;
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} else {
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ds.top().next();
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cur = ds.top().space()->clone();
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if (tracer)
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tracer.ei()->init(tracer.wid(), nid, a, *cur, *ch);
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cur->commit(*ch,a);
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}
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node++;
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d++;
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}
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check_discrepancy:
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if (d == 0) {
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Space* s = cur;
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while (s->status(*this) == SS_BRANCH) {
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if (stop(opt)) {
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cur = s;
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return nullptr;
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}
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const Choice* ch = s->choice();
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if (ch->alternatives() > 1)
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exhausted = false;
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if (tracer) {
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unsigned int nid = tracer.nid();
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SearchTracer::NodeInfo ni(SearchTracer::NodeType::BRANCH,
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tracer.wid(), nid, *s, ch);
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tracer.node(*tracer.ei(),ni);
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if (tracer)
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tracer.ei()->init(tracer.wid(), nid, 0, *cur, *ch);
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}
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s->commit(*ch,0);
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node++;
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delete ch;
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}
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cur = nullptr;
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if (s->failed()) {
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if (tracer) {
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SearchTracer::NodeInfo ni(SearchTracer::NodeType::FAILED,
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tracer.wid(), tracer.nid(), *s);
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tracer.node(*tracer.ei(),ni);
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}
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fail++;
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delete s;
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goto backtrack;
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} else {
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if (tracer) {
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SearchTracer::NodeInfo ni(SearchTracer::NodeType::SOLVED,
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tracer.wid(), tracer.nid(), *s);
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tracer.node(*tracer.ei(),ni);
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}
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// Deletes all pending branchings
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(void) s->choice();
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return s;
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}
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} else {
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node++;
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switch (cur->status(*this)) {
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case SS_FAILED:
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if (tracer) {
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SearchTracer::NodeInfo ni(SearchTracer::NodeType::FAILED,
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tracer.wid(), tracer.nid(), *cur);
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tracer.node(*tracer.ei(),ni);
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}
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fail++;
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delete cur;
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cur = nullptr;
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goto backtrack;
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case SS_SOLVED:
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if (tracer) {
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tracer.skip(*tracer.ei());
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}
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delete cur;
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cur = nullptr;
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goto backtrack;
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case SS_BRANCH:
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{
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const Choice* ch = cur->choice();
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unsigned int alt = ch->alternatives();
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unsigned int nid = tracer.nid();
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if (tracer) {
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SearchTracer::NodeInfo ni(SearchTracer::NodeType::BRANCH,
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tracer.wid(), nid, *cur, ch);
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tracer.node(*tracer.ei(),ni);
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}
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if (alt > 1) {
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if (d < alt-1)
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exhausted = false;
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unsigned int d_a = (d >= alt-1) ? alt-1 : d;
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Space* cc = cur->clone();
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Node sn(cc,ch,d_a-1,nid);
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ds.push(sn);
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stack_depth(static_cast<unsigned long int>(ds.entries()));
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if (tracer)
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tracer.ei()->init(tracer.wid(), nid, d_a, *cur, *ch);
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cur->commit(*ch,d_a);
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d -= d_a;
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} else {
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if (tracer)
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tracer.ei()->init(tracer.wid(), nid, 0, *cur, *ch);
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cur->commit(*ch,0);
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node++;
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delete ch;
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}
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goto check_discrepancy;
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}
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default: GECODE_NEVER;
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}
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}
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}
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}
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template<class Tracer>
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forceinline
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LDS<Tracer>::LDS(Space* s, const Options& o)
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: opt(o), e(opt), root(nullptr), d(0) {
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e.node = 1;
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if (s->status(e) == SS_FAILED) {
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e.fail++;
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e.init(nullptr);
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} else {
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Space* c = snapshot(s,opt);
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if (opt.d_l > 0) {
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root = c->clone();
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}
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e.init(c);
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}
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}
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template<class Tracer>
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Space*
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LDS<Tracer>::next(void) {
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while (true) {
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Space* s = e.next(opt);
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if (s != nullptr)
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return s;
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if (((s == nullptr) && e.stopped()) || (++d > opt.d_l) || e.done())
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break;
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if (d == opt.d_l) {
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if (root != nullptr)
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e.reset(root,d);
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root = nullptr;
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} else if (root != nullptr) {
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e.reset(root->clone(),d);
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}
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}
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return nullptr;
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}
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template<class Tracer>
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bool
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LDS<Tracer>::stopped(void) const {
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return e.stopped();
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}
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template<class Tracer>
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Statistics
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LDS<Tracer>::statistics(void) const {
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return e.statistics();
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}
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template<class Tracer>
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forceinline void
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LDS<Tracer>::reset(Space* s) {
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delete root; root=nullptr; d=0;
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e.node = 1;
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if ((s == nullptr) || (s->status(e) == SS_FAILED)) {
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delete s;
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e.fail++;
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e.reset(nullptr,0);
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} else {
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if (opt.d_l > 0) {
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root = s->clone();
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}
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e.reset(s,0);
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}
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}
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template<class Tracer>
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forceinline void
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LDS<Tracer>::constrain(const Space& b) {
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(void) b;
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assert(false);
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}
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template<class Tracer>
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LDS<Tracer>::~LDS(void) {
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delete root;
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}
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}}}
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// STATISTICS: search-seq
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