COIN-OR::LEMON - Graph Library

source: lemon/lemon/smart_graph.h @ 1187:4c89e925cfe2

Last change on this file since 1187:4c89e925cfe2 was 1187:4c89e925cfe2, checked in by Balazs Dezso <deba@…>, 9 years ago

SmartBpGraph? implementation (#69)

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1/* -*- mode: C++; indent-tabs-mode: nil; -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library.
4 *
5 * Copyright (C) 2003-2010
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 */
18
19#ifndef LEMON_SMART_GRAPH_H
20#define LEMON_SMART_GRAPH_H
21
22///\ingroup graphs
23///\file
24///\brief SmartDigraph and SmartGraph classes.
25
26#include <vector>
27
28#include <lemon/core.h>
29#include <lemon/error.h>
30#include <lemon/bits/graph_extender.h>
31
32namespace lemon {
33
34  class SmartDigraph;
35
36  class SmartDigraphBase {
37  protected:
38
39    struct NodeT
40    {
41      int first_in, first_out;
42      NodeT() {}
43    };
44    struct ArcT
45    {
46      int target, source, next_in, next_out;
47      ArcT() {}
48    };
49
50    std::vector<NodeT> nodes;
51    std::vector<ArcT> arcs;
52
53  public:
54
55    typedef SmartDigraphBase Digraph;
56
57    class Node;
58    class Arc;
59
60  public:
61
62    SmartDigraphBase() : nodes(), arcs() { }
63    SmartDigraphBase(const SmartDigraphBase &_g)
64      : nodes(_g.nodes), arcs(_g.arcs) { }
65
66    typedef True NodeNumTag;
67    typedef True ArcNumTag;
68
69    int nodeNum() const { return nodes.size(); }
70    int arcNum() const { return arcs.size(); }
71
72    int maxNodeId() const { return nodes.size()-1; }
73    int maxArcId() const { return arcs.size()-1; }
74
75    Node addNode() {
76      int n = nodes.size();
77      nodes.push_back(NodeT());
78      nodes[n].first_in = -1;
79      nodes[n].first_out = -1;
80      return Node(n);
81    }
82
83    Arc addArc(Node u, Node v) {
84      int n = arcs.size();
85      arcs.push_back(ArcT());
86      arcs[n].source = u._id;
87      arcs[n].target = v._id;
88      arcs[n].next_out = nodes[u._id].first_out;
89      arcs[n].next_in = nodes[v._id].first_in;
90      nodes[u._id].first_out = nodes[v._id].first_in = n;
91
92      return Arc(n);
93    }
94
95    void clear() {
96      arcs.clear();
97      nodes.clear();
98    }
99
100    Node source(Arc a) const { return Node(arcs[a._id].source); }
101    Node target(Arc a) const { return Node(arcs[a._id].target); }
102
103    static int id(Node v) { return v._id; }
104    static int id(Arc a) { return a._id; }
105
106    static Node nodeFromId(int id) { return Node(id);}
107    static Arc arcFromId(int id) { return Arc(id);}
108
109    bool valid(Node n) const {
110      return n._id >= 0 && n._id < static_cast<int>(nodes.size());
111    }
112    bool valid(Arc a) const {
113      return a._id >= 0 && a._id < static_cast<int>(arcs.size());
114    }
115
116    class Node {
117      friend class SmartDigraphBase;
118      friend class SmartDigraph;
119
120    protected:
121      int _id;
122      explicit Node(int id) : _id(id) {}
123    public:
124      Node() {}
125      Node (Invalid) : _id(-1) {}
126      bool operator==(const Node i) const {return _id == i._id;}
127      bool operator!=(const Node i) const {return _id != i._id;}
128      bool operator<(const Node i) const {return _id < i._id;}
129    };
130
131
132    class Arc {
133      friend class SmartDigraphBase;
134      friend class SmartDigraph;
135
136    protected:
137      int _id;
138      explicit Arc(int id) : _id(id) {}
139    public:
140      Arc() { }
141      Arc (Invalid) : _id(-1) {}
142      bool operator==(const Arc i) const {return _id == i._id;}
143      bool operator!=(const Arc i) const {return _id != i._id;}
144      bool operator<(const Arc i) const {return _id < i._id;}
145    };
146
147    void first(Node& node) const {
148      node._id = nodes.size() - 1;
149    }
150
151    static void next(Node& node) {
152      --node._id;
153    }
154
155    void first(Arc& arc) const {
156      arc._id = arcs.size() - 1;
157    }
158
159    static void next(Arc& arc) {
160      --arc._id;
161    }
162
163    void firstOut(Arc& arc, const Node& node) const {
164      arc._id = nodes[node._id].first_out;
165    }
166
167    void nextOut(Arc& arc) const {
168      arc._id = arcs[arc._id].next_out;
169    }
170
171    void firstIn(Arc& arc, const Node& node) const {
172      arc._id = nodes[node._id].first_in;
173    }
174
175    void nextIn(Arc& arc) const {
176      arc._id = arcs[arc._id].next_in;
177    }
178
179  };
180
181  typedef DigraphExtender<SmartDigraphBase> ExtendedSmartDigraphBase;
182
183  ///\ingroup graphs
184  ///
185  ///\brief A smart directed graph class.
186  ///
187  ///\ref SmartDigraph is a simple and fast digraph implementation.
188  ///It is also quite memory efficient but at the price
189  ///that it does not support node and arc deletion
190  ///(except for the Snapshot feature).
191  ///
192  ///This type fully conforms to the \ref concepts::Digraph "Digraph concept"
193  ///and it also provides some additional functionalities.
194  ///Most of its member functions and nested classes are documented
195  ///only in the concept class.
196  ///
197  ///This class provides constant time counting for nodes and arcs.
198  ///
199  ///\sa concepts::Digraph
200  ///\sa SmartGraph
201  class SmartDigraph : public ExtendedSmartDigraphBase {
202    typedef ExtendedSmartDigraphBase Parent;
203
204  private:
205    /// Digraphs are \e not copy constructible. Use DigraphCopy instead.
206    SmartDigraph(const SmartDigraph &) : ExtendedSmartDigraphBase() {};
207    /// \brief Assignment of a digraph to another one is \e not allowed.
208    /// Use DigraphCopy instead.
209    void operator=(const SmartDigraph &) {}
210
211  public:
212
213    /// Constructor
214
215    /// Constructor.
216    ///
217    SmartDigraph() {};
218
219    ///Add a new node to the digraph.
220
221    ///This function adds a new node to the digraph.
222    ///\return The new node.
223    Node addNode() { return Parent::addNode(); }
224
225    ///Add a new arc to the digraph.
226
227    ///This function adds a new arc to the digraph with source node \c s
228    ///and target node \c t.
229    ///\return The new arc.
230    Arc addArc(Node s, Node t) {
231      return Parent::addArc(s, t);
232    }
233
234    /// \brief Node validity check
235    ///
236    /// This function gives back \c true if the given node is valid,
237    /// i.e. it is a real node of the digraph.
238    ///
239    /// \warning A removed node (using Snapshot) could become valid again
240    /// if new nodes are added to the digraph.
241    bool valid(Node n) const { return Parent::valid(n); }
242
243    /// \brief Arc validity check
244    ///
245    /// This function gives back \c true if the given arc is valid,
246    /// i.e. it is a real arc of the digraph.
247    ///
248    /// \warning A removed arc (using Snapshot) could become valid again
249    /// if new arcs are added to the graph.
250    bool valid(Arc a) const { return Parent::valid(a); }
251
252    ///Split a node.
253
254    ///This function splits the given node. First, a new node is added
255    ///to the digraph, then the source of each outgoing arc of node \c n
256    ///is moved to this new node.
257    ///If the second parameter \c connect is \c true (this is the default
258    ///value), then a new arc from node \c n to the newly created node
259    ///is also added.
260    ///\return The newly created node.
261    ///
262    ///\note All iterators remain valid.
263    ///
264    ///\warning This functionality cannot be used together with the Snapshot
265    ///feature.
266    Node split(Node n, bool connect = true)
267    {
268      Node b = addNode();
269      nodes[b._id].first_out=nodes[n._id].first_out;
270      nodes[n._id].first_out=-1;
271      for(int i=nodes[b._id].first_out; i!=-1; i=arcs[i].next_out) {
272        arcs[i].source=b._id;
273      }
274      if(connect) addArc(n,b);
275      return b;
276    }
277
278    ///Clear the digraph.
279
280    ///This function erases all nodes and arcs from the digraph.
281    ///
282    void clear() {
283      Parent::clear();
284    }
285
286    /// Reserve memory for nodes.
287
288    /// Using this function, it is possible to avoid superfluous memory
289    /// allocation: if you know that the digraph you want to build will
290    /// be large (e.g. it will contain millions of nodes and/or arcs),
291    /// then it is worth reserving space for this amount before starting
292    /// to build the digraph.
293    /// \sa reserveArc()
294    void reserveNode(int n) { nodes.reserve(n); };
295
296    /// Reserve memory for arcs.
297
298    /// Using this function, it is possible to avoid superfluous memory
299    /// allocation: if you know that the digraph you want to build will
300    /// be large (e.g. it will contain millions of nodes and/or arcs),
301    /// then it is worth reserving space for this amount before starting
302    /// to build the digraph.
303    /// \sa reserveNode()
304    void reserveArc(int m) { arcs.reserve(m); };
305
306  public:
307
308    class Snapshot;
309
310  protected:
311
312    void restoreSnapshot(const Snapshot &s)
313    {
314      while(s.arc_num<arcs.size()) {
315        Arc arc = arcFromId(arcs.size()-1);
316        Parent::notifier(Arc()).erase(arc);
317        nodes[arcs.back().source].first_out=arcs.back().next_out;
318        nodes[arcs.back().target].first_in=arcs.back().next_in;
319        arcs.pop_back();
320      }
321      while(s.node_num<nodes.size()) {
322        Node node = nodeFromId(nodes.size()-1);
323        Parent::notifier(Node()).erase(node);
324        nodes.pop_back();
325      }
326    }
327
328  public:
329
330    ///Class to make a snapshot of the digraph and to restore it later.
331
332    ///Class to make a snapshot of the digraph and to restore it later.
333    ///
334    ///The newly added nodes and arcs can be removed using the
335    ///restore() function. This is the only way for deleting nodes and/or
336    ///arcs from a SmartDigraph structure.
337    ///
338    ///\note After a state is restored, you cannot restore a later state,
339    ///i.e. you cannot add the removed nodes and arcs again using
340    ///another Snapshot instance.
341    ///
342    ///\warning Node splitting cannot be restored.
343    ///\warning The validity of the snapshot is not stored due to
344    ///performance reasons. If you do not use the snapshot correctly,
345    ///it can cause broken program, invalid or not restored state of
346    ///the digraph or no change.
347    class Snapshot
348    {
349      SmartDigraph *_graph;
350    protected:
351      friend class SmartDigraph;
352      unsigned int node_num;
353      unsigned int arc_num;
354    public:
355      ///Default constructor.
356
357      ///Default constructor.
358      ///You have to call save() to actually make a snapshot.
359      Snapshot() : _graph(0) {}
360      ///Constructor that immediately makes a snapshot
361
362      ///This constructor immediately makes a snapshot of the given digraph.
363      ///
364      Snapshot(SmartDigraph &gr) : _graph(&gr) {
365        node_num=_graph->nodes.size();
366        arc_num=_graph->arcs.size();
367      }
368
369      ///Make a snapshot.
370
371      ///This function makes a snapshot of the given digraph.
372      ///It can be called more than once. In case of a repeated
373      ///call, the previous snapshot gets lost.
374      void save(SmartDigraph &gr) {
375        _graph=&gr;
376        node_num=_graph->nodes.size();
377        arc_num=_graph->arcs.size();
378      }
379
380      ///Undo the changes until a snapshot.
381
382      ///This function undos the changes until the last snapshot
383      ///created by save() or Snapshot(SmartDigraph&).
384      void restore()
385      {
386        _graph->restoreSnapshot(*this);
387      }
388    };
389  };
390
391
392  class SmartGraphBase {
393
394  protected:
395
396    struct NodeT {
397      int first_out;
398    };
399
400    struct ArcT {
401      int target;
402      int next_out;
403    };
404
405    std::vector<NodeT> nodes;
406    std::vector<ArcT> arcs;
407
408  public:
409
410    typedef SmartGraphBase Graph;
411
412    class Node;
413    class Arc;
414    class Edge;
415
416    class Node {
417      friend class SmartGraphBase;
418    protected:
419
420      int _id;
421      explicit Node(int id) { _id = id;}
422
423    public:
424      Node() {}
425      Node (Invalid) { _id = -1; }
426      bool operator==(const Node& node) const {return _id == node._id;}
427      bool operator!=(const Node& node) const {return _id != node._id;}
428      bool operator<(const Node& node) const {return _id < node._id;}
429    };
430
431    class Edge {
432      friend class SmartGraphBase;
433    protected:
434
435      int _id;
436      explicit Edge(int id) { _id = id;}
437
438    public:
439      Edge() {}
440      Edge (Invalid) { _id = -1; }
441      bool operator==(const Edge& arc) const {return _id == arc._id;}
442      bool operator!=(const Edge& arc) const {return _id != arc._id;}
443      bool operator<(const Edge& arc) const {return _id < arc._id;}
444    };
445
446    class Arc {
447      friend class SmartGraphBase;
448    protected:
449
450      int _id;
451      explicit Arc(int id) { _id = id;}
452
453    public:
454      operator Edge() const {
455        return _id != -1 ? edgeFromId(_id / 2) : INVALID;
456      }
457
458      Arc() {}
459      Arc (Invalid) { _id = -1; }
460      bool operator==(const Arc& arc) const {return _id == arc._id;}
461      bool operator!=(const Arc& arc) const {return _id != arc._id;}
462      bool operator<(const Arc& arc) const {return _id < arc._id;}
463    };
464
465
466
467    SmartGraphBase()
468      : nodes(), arcs() {}
469
470    typedef True NodeNumTag;
471    typedef True EdgeNumTag;
472    typedef True ArcNumTag;
473
474    int nodeNum() const { return nodes.size(); }
475    int edgeNum() const { return arcs.size() / 2; }
476    int arcNum() const { return arcs.size(); }
477
478    int maxNodeId() const { return nodes.size()-1; }
479    int maxEdgeId() const { return arcs.size() / 2 - 1; }
480    int maxArcId() const { return arcs.size()-1; }
481
482    Node source(Arc e) const { return Node(arcs[e._id ^ 1].target); }
483    Node target(Arc e) const { return Node(arcs[e._id].target); }
484
485    Node u(Edge e) const { return Node(arcs[2 * e._id].target); }
486    Node v(Edge e) const { return Node(arcs[2 * e._id + 1].target); }
487
488    static bool direction(Arc e) {
489      return (e._id & 1) == 1;
490    }
491
492    static Arc direct(Edge e, bool d) {
493      return Arc(e._id * 2 + (d ? 1 : 0));
494    }
495
496    void first(Node& node) const {
497      node._id = nodes.size() - 1;
498    }
499
500    static void next(Node& node) {
501      --node._id;
502    }
503
504    void first(Arc& arc) const {
505      arc._id = arcs.size() - 1;
506    }
507
508    static void next(Arc& arc) {
509      --arc._id;
510    }
511
512    void first(Edge& arc) const {
513      arc._id = arcs.size() / 2 - 1;
514    }
515
516    static void next(Edge& arc) {
517      --arc._id;
518    }
519
520    void firstOut(Arc &arc, const Node& v) const {
521      arc._id = nodes[v._id].first_out;
522    }
523    void nextOut(Arc &arc) const {
524      arc._id = arcs[arc._id].next_out;
525    }
526
527    void firstIn(Arc &arc, const Node& v) const {
528      arc._id = ((nodes[v._id].first_out) ^ 1);
529      if (arc._id == -2) arc._id = -1;
530    }
531    void nextIn(Arc &arc) const {
532      arc._id = ((arcs[arc._id ^ 1].next_out) ^ 1);
533      if (arc._id == -2) arc._id = -1;
534    }
535
536    void firstInc(Edge &arc, bool& d, const Node& v) const {
537      int de = nodes[v._id].first_out;
538      if (de != -1) {
539        arc._id = de / 2;
540        d = ((de & 1) == 1);
541      } else {
542        arc._id = -1;
543        d = true;
544      }
545    }
546    void nextInc(Edge &arc, bool& d) const {
547      int de = (arcs[(arc._id * 2) | (d ? 1 : 0)].next_out);
548      if (de != -1) {
549        arc._id = de / 2;
550        d = ((de & 1) == 1);
551      } else {
552        arc._id = -1;
553        d = true;
554      }
555    }
556
557    static int id(Node v) { return v._id; }
558    static int id(Arc e) { return e._id; }
559    static int id(Edge e) { return e._id; }
560
561    static Node nodeFromId(int id) { return Node(id);}
562    static Arc arcFromId(int id) { return Arc(id);}
563    static Edge edgeFromId(int id) { return Edge(id);}
564
565    bool valid(Node n) const {
566      return n._id >= 0 && n._id < static_cast<int>(nodes.size());
567    }
568    bool valid(Arc a) const {
569      return a._id >= 0 && a._id < static_cast<int>(arcs.size());
570    }
571    bool valid(Edge e) const {
572      return e._id >= 0 && 2 * e._id < static_cast<int>(arcs.size());
573    }
574
575    Node addNode() {
576      int n = nodes.size();
577      nodes.push_back(NodeT());
578      nodes[n].first_out = -1;
579
580      return Node(n);
581    }
582
583    Edge addEdge(Node u, Node v) {
584      int n = arcs.size();
585      arcs.push_back(ArcT());
586      arcs.push_back(ArcT());
587
588      arcs[n].target = u._id;
589      arcs[n | 1].target = v._id;
590
591      arcs[n].next_out = nodes[v._id].first_out;
592      nodes[v._id].first_out = n;
593
594      arcs[n | 1].next_out = nodes[u._id].first_out;
595      nodes[u._id].first_out = (n | 1);
596
597      return Edge(n / 2);
598    }
599
600    void clear() {
601      arcs.clear();
602      nodes.clear();
603    }
604
605  };
606
607  typedef GraphExtender<SmartGraphBase> ExtendedSmartGraphBase;
608
609  /// \ingroup graphs
610  ///
611  /// \brief A smart undirected graph class.
612  ///
613  /// \ref SmartGraph is a simple and fast graph implementation.
614  /// It is also quite memory efficient but at the price
615  /// that it does not support node and edge deletion
616  /// (except for the Snapshot feature).
617  ///
618  /// This type fully conforms to the \ref concepts::Graph "Graph concept"
619  /// and it also provides some additional functionalities.
620  /// Most of its member functions and nested classes are documented
621  /// only in the concept class.
622  ///
623  /// This class provides constant time counting for nodes, edges and arcs.
624  ///
625  /// \sa concepts::Graph
626  /// \sa SmartDigraph
627  class SmartGraph : public ExtendedSmartGraphBase {
628    typedef ExtendedSmartGraphBase Parent;
629
630  private:
631    /// Graphs are \e not copy constructible. Use GraphCopy instead.
632    SmartGraph(const SmartGraph &) : ExtendedSmartGraphBase() {};
633    /// \brief Assignment of a graph to another one is \e not allowed.
634    /// Use GraphCopy instead.
635    void operator=(const SmartGraph &) {}
636
637  public:
638
639    /// Constructor
640
641    /// Constructor.
642    ///
643    SmartGraph() {}
644
645    /// \brief Add a new node to the graph.
646    ///
647    /// This function adds a new node to the graph.
648    /// \return The new node.
649    Node addNode() { return Parent::addNode(); }
650
651    /// \brief Add a new edge to the graph.
652    ///
653    /// This function adds a new edge to the graph between nodes
654    /// \c u and \c v with inherent orientation from node \c u to
655    /// node \c v.
656    /// \return The new edge.
657    Edge addEdge(Node u, Node v) {
658      return Parent::addEdge(u, v);
659    }
660
661    /// \brief Node validity check
662    ///
663    /// This function gives back \c true if the given node is valid,
664    /// i.e. it is a real node of the graph.
665    ///
666    /// \warning A removed node (using Snapshot) could become valid again
667    /// if new nodes are added to the graph.
668    bool valid(Node n) const { return Parent::valid(n); }
669
670    /// \brief Edge validity check
671    ///
672    /// This function gives back \c true if the given edge is valid,
673    /// i.e. it is a real edge of the graph.
674    ///
675    /// \warning A removed edge (using Snapshot) could become valid again
676    /// if new edges are added to the graph.
677    bool valid(Edge e) const { return Parent::valid(e); }
678
679    /// \brief Arc validity check
680    ///
681    /// This function gives back \c true if the given arc is valid,
682    /// i.e. it is a real arc of the graph.
683    ///
684    /// \warning A removed arc (using Snapshot) could become valid again
685    /// if new edges are added to the graph.
686    bool valid(Arc a) const { return Parent::valid(a); }
687
688    ///Clear the graph.
689
690    ///This function erases all nodes and arcs from the graph.
691    ///
692    void clear() {
693      Parent::clear();
694    }
695
696    /// Reserve memory for nodes.
697
698    /// Using this function, it is possible to avoid superfluous memory
699    /// allocation: if you know that the graph you want to build will
700    /// be large (e.g. it will contain millions of nodes and/or edges),
701    /// then it is worth reserving space for this amount before starting
702    /// to build the graph.
703    /// \sa reserveEdge()
704    void reserveNode(int n) { nodes.reserve(n); };
705
706    /// Reserve memory for edges.
707
708    /// Using this function, it is possible to avoid superfluous memory
709    /// allocation: if you know that the graph you want to build will
710    /// be large (e.g. it will contain millions of nodes and/or edges),
711    /// then it is worth reserving space for this amount before starting
712    /// to build the graph.
713    /// \sa reserveNode()
714    void reserveEdge(int m) { arcs.reserve(2 * m); };
715
716  public:
717
718    class Snapshot;
719
720  protected:
721
722    void saveSnapshot(Snapshot &s)
723    {
724      s._graph = this;
725      s.node_num = nodes.size();
726      s.arc_num = arcs.size();
727    }
728
729    void restoreSnapshot(const Snapshot &s)
730    {
731      while(s.arc_num<arcs.size()) {
732        int n=arcs.size()-1;
733        Edge arc=edgeFromId(n/2);
734        Parent::notifier(Edge()).erase(arc);
735        std::vector<Arc> dir;
736        dir.push_back(arcFromId(n));
737        dir.push_back(arcFromId(n-1));
738        Parent::notifier(Arc()).erase(dir);
739        nodes[arcs[n-1].target].first_out=arcs[n].next_out;
740        nodes[arcs[n].target].first_out=arcs[n-1].next_out;
741        arcs.pop_back();
742        arcs.pop_back();
743      }
744      while(s.node_num<nodes.size()) {
745        int n=nodes.size()-1;
746        Node node = nodeFromId(n);
747        Parent::notifier(Node()).erase(node);
748        nodes.pop_back();
749      }
750    }
751
752  public:
753
754    ///Class to make a snapshot of the graph and to restore it later.
755
756    ///Class to make a snapshot of the graph and to restore it later.
757    ///
758    ///The newly added nodes and edges can be removed using the
759    ///restore() function. This is the only way for deleting nodes and/or
760    ///edges from a SmartGraph structure.
761    ///
762    ///\note After a state is restored, you cannot restore a later state,
763    ///i.e. you cannot add the removed nodes and edges again using
764    ///another Snapshot instance.
765    ///
766    ///\warning The validity of the snapshot is not stored due to
767    ///performance reasons. If you do not use the snapshot correctly,
768    ///it can cause broken program, invalid or not restored state of
769    ///the graph or no change.
770    class Snapshot
771    {
772      SmartGraph *_graph;
773    protected:
774      friend class SmartGraph;
775      unsigned int node_num;
776      unsigned int arc_num;
777    public:
778      ///Default constructor.
779
780      ///Default constructor.
781      ///You have to call save() to actually make a snapshot.
782      Snapshot() : _graph(0) {}
783      ///Constructor that immediately makes a snapshot
784
785      /// This constructor immediately makes a snapshot of the given graph.
786      ///
787      Snapshot(SmartGraph &gr) {
788        gr.saveSnapshot(*this);
789      }
790
791      ///Make a snapshot.
792
793      ///This function makes a snapshot of the given graph.
794      ///It can be called more than once. In case of a repeated
795      ///call, the previous snapshot gets lost.
796      void save(SmartGraph &gr)
797      {
798        gr.saveSnapshot(*this);
799      }
800
801      ///Undo the changes until the last snapshot.
802
803      ///This function undos the changes until the last snapshot
804      ///created by save() or Snapshot(SmartGraph&).
805      void restore()
806      {
807        _graph->restoreSnapshot(*this);
808      }
809    };
810  };
811
812  class SmartBpGraphBase {
813
814  protected:
815
816    struct NodeT {
817      int first_out;
818      int partition_next;
819      int partition_index;
820      bool red;
821    };
822
823    struct ArcT {
824      int target;
825      int next_out;
826    };
827
828    std::vector<NodeT> nodes;
829    std::vector<ArcT> arcs;
830
831    int first_red, first_blue;
832
833  public:
834
835    typedef SmartBpGraphBase Graph;
836
837    class Node;
838    class Arc;
839    class Edge;
840
841    class Node {
842      friend class SmartBpGraphBase;
843    protected:
844
845      int _id;
846      explicit Node(int id) { _id = id;}
847
848    public:
849      Node() {}
850      Node (Invalid) { _id = -1; }
851      bool operator==(const Node& node) const {return _id == node._id;}
852      bool operator!=(const Node& node) const {return _id != node._id;}
853      bool operator<(const Node& node) const {return _id < node._id;}
854    };
855
856    class Edge {
857      friend class SmartBpGraphBase;
858    protected:
859
860      int _id;
861      explicit Edge(int id) { _id = id;}
862
863    public:
864      Edge() {}
865      Edge (Invalid) { _id = -1; }
866      bool operator==(const Edge& arc) const {return _id == arc._id;}
867      bool operator!=(const Edge& arc) const {return _id != arc._id;}
868      bool operator<(const Edge& arc) const {return _id < arc._id;}
869    };
870
871    class Arc {
872      friend class SmartBpGraphBase;
873    protected:
874
875      int _id;
876      explicit Arc(int id) { _id = id;}
877
878    public:
879      operator Edge() const {
880        return _id != -1 ? edgeFromId(_id / 2) : INVALID;
881      }
882
883      Arc() {}
884      Arc (Invalid) { _id = -1; }
885      bool operator==(const Arc& arc) const {return _id == arc._id;}
886      bool operator!=(const Arc& arc) const {return _id != arc._id;}
887      bool operator<(const Arc& arc) const {return _id < arc._id;}
888    };
889
890
891
892    SmartBpGraphBase()
893      : nodes(), arcs(), first_red(-1), first_blue(-1) {}
894
895    typedef True NodeNumTag;
896    typedef True EdgeNumTag;
897    typedef True ArcNumTag;
898
899    int nodeNum() const { return nodes.size(); }
900    int redNum() const {
901      return first_red == -1 ? 0 : nodes[first_red].partition_index + 1;
902    }
903    int blueNum() const {
904      return first_blue == -1 ? 0 : nodes[first_blue].partition_index + 1;
905    }
906    int edgeNum() const { return arcs.size() / 2; }
907    int arcNum() const { return arcs.size(); }
908
909    int maxNodeId() const { return nodes.size()-1; }
910    int maxRedId() const {
911      return first_red == -1 ? -1 : nodes[first_red].partition_index;
912    }
913    int maxBlueId() const {
914      return first_blue == -1 ? -1 : nodes[first_blue].partition_index;
915    }
916    int maxEdgeId() const { return arcs.size() / 2 - 1; }
917    int maxArcId() const { return arcs.size()-1; }
918
919    bool red(Node n) const { return nodes[n._id].red; }
920    bool blue(Node n) const { return !nodes[n._id].red; }
921
922    Node source(Arc a) const { return Node(arcs[a._id ^ 1].target); }
923    Node target(Arc a) const { return Node(arcs[a._id].target); }
924
925    Node redNode(Edge e) const { return Node(arcs[2 * e._id].target); }
926    Node blueNode(Edge e) const { return Node(arcs[2 * e._id + 1].target); }
927
928    Node u(Edge e) const { return redNode(e); }
929    Node v(Edge e) const { return blueNode(e); }
930
931    static bool direction(Arc a) {
932      return (a._id & 1) == 1;
933    }
934
935    static Arc direct(Edge e, bool d) {
936      return Arc(e._id * 2 + (d ? 1 : 0));
937    }
938
939    void first(Node& node) const {
940      node._id = nodes.size() - 1;
941    }
942
943    static void next(Node& node) {
944      --node._id;
945    }
946
947    void firstRed(Node& node) const {
948      node._id = first_red;
949    }
950
951    void nextRed(Node& node) const {
952      node._id = nodes[node._id].partition_next;
953    }
954
955    void firstBlue(Node& node) const {
956      node._id = first_blue;
957    }
958
959    void nextBlue(Node& node) const {
960      node._id = nodes[node._id].partition_next;
961    }
962
963    void first(Arc& arc) const {
964      arc._id = arcs.size() - 1;
965    }
966
967    static void next(Arc& arc) {
968      --arc._id;
969    }
970
971    void first(Edge& arc) const {
972      arc._id = arcs.size() / 2 - 1;
973    }
974
975    static void next(Edge& arc) {
976      --arc._id;
977    }
978
979    void firstOut(Arc &arc, const Node& v) const {
980      arc._id = nodes[v._id].first_out;
981    }
982    void nextOut(Arc &arc) const {
983      arc._id = arcs[arc._id].next_out;
984    }
985
986    void firstIn(Arc &arc, const Node& v) const {
987      arc._id = ((nodes[v._id].first_out) ^ 1);
988      if (arc._id == -2) arc._id = -1;
989    }
990    void nextIn(Arc &arc) const {
991      arc._id = ((arcs[arc._id ^ 1].next_out) ^ 1);
992      if (arc._id == -2) arc._id = -1;
993    }
994
995    void firstInc(Edge &arc, bool& d, const Node& v) const {
996      int de = nodes[v._id].first_out;
997      if (de != -1) {
998        arc._id = de / 2;
999        d = ((de & 1) == 1);
1000      } else {
1001        arc._id = -1;
1002        d = true;
1003      }
1004    }
1005    void nextInc(Edge &arc, bool& d) const {
1006      int de = (arcs[(arc._id * 2) | (d ? 1 : 0)].next_out);
1007      if (de != -1) {
1008        arc._id = de / 2;
1009        d = ((de & 1) == 1);
1010      } else {
1011        arc._id = -1;
1012        d = true;
1013      }
1014    }
1015
1016    static int id(Node v) { return v._id; }
1017    int redId(Node v) const {
1018      LEMON_DEBUG(nodes[v._id].red, "Node has to be red");
1019      return nodes[v._id].partition_index;
1020    }
1021    int blueId(Node v) const {
1022      LEMON_DEBUG(nodes[v._id].red, "Node has to be blue");
1023      return nodes[v._id].partition_index;
1024    }
1025    static int id(Arc e) { return e._id; }
1026    static int id(Edge e) { return e._id; }
1027
1028    static Node nodeFromId(int id) { return Node(id);}
1029    static Arc arcFromId(int id) { return Arc(id);}
1030    static Edge edgeFromId(int id) { return Edge(id);}
1031
1032    bool valid(Node n) const {
1033      return n._id >= 0 && n._id < static_cast<int>(nodes.size());
1034    }
1035    bool valid(Arc a) const {
1036      return a._id >= 0 && a._id < static_cast<int>(arcs.size());
1037    }
1038    bool valid(Edge e) const {
1039      return e._id >= 0 && 2 * e._id < static_cast<int>(arcs.size());
1040    }
1041
1042    Node addRedNode() {
1043      int n = nodes.size();
1044      nodes.push_back(NodeT());
1045      nodes[n].first_out = -1;
1046      nodes[n].red = true;
1047      if (first_red == -1) {
1048        nodes[n].partition_index = 0;
1049      } else {
1050        nodes[n].partition_index = nodes[first_red].partition_index + 1;
1051      }
1052      nodes[n].partition_next = first_red;
1053      first_red = n;
1054
1055      return Node(n);
1056    }
1057
1058    Node addBlueNode() {
1059      int n = nodes.size();
1060      nodes.push_back(NodeT());
1061      nodes[n].first_out = -1;
1062      nodes[n].red = false;
1063      if (first_blue == -1) {
1064        nodes[n].partition_index = 0;
1065      } else {
1066        nodes[n].partition_index = nodes[first_blue].partition_index + 1;
1067      }
1068      nodes[n].partition_next = first_blue;
1069      first_blue = n;
1070
1071      return Node(n);
1072    }
1073
1074    Edge addEdge(Node u, Node v) {
1075      int n = arcs.size();
1076      arcs.push_back(ArcT());
1077      arcs.push_back(ArcT());
1078
1079      arcs[n].target = u._id;
1080      arcs[n | 1].target = v._id;
1081
1082      arcs[n].next_out = nodes[v._id].first_out;
1083      nodes[v._id].first_out = n;
1084
1085      arcs[n | 1].next_out = nodes[u._id].first_out;
1086      nodes[u._id].first_out = (n | 1);
1087
1088      return Edge(n / 2);
1089    }
1090
1091    void clear() {
1092      arcs.clear();
1093      nodes.clear();
1094      first_red = -1;
1095      first_blue = -1;
1096    }
1097
1098  };
1099
1100  typedef BpGraphExtender<SmartBpGraphBase> ExtendedSmartBpGraphBase;
1101
1102  /// \ingroup graphs
1103  ///
1104  /// \brief A smart undirected graph class.
1105  ///
1106  /// \ref SmartBpGraph is a simple and fast graph implementation.
1107  /// It is also quite memory efficient but at the price
1108  /// that it does not support node and edge deletion
1109  /// (except for the Snapshot feature).
1110  ///
1111  /// This type fully conforms to the \ref concepts::Graph "Graph concept"
1112  /// and it also provides some additional functionalities.
1113  /// Most of its member functions and nested classes are documented
1114  /// only in the concept class.
1115  ///
1116  /// This class provides constant time counting for nodes, edges and arcs.
1117  ///
1118  /// \sa concepts::Graph
1119  /// \sa SmartDigraph
1120  class SmartBpGraph : public ExtendedSmartBpGraphBase {
1121    typedef ExtendedSmartBpGraphBase Parent;
1122
1123  private:
1124    /// Graphs are \e not copy constructible. Use GraphCopy instead.
1125    SmartBpGraph(const SmartBpGraph &) : ExtendedSmartBpGraphBase() {};
1126    /// \brief Assignment of a graph to another one is \e not allowed.
1127    /// Use GraphCopy instead.
1128    void operator=(const SmartBpGraph &) {}
1129
1130  public:
1131
1132    /// Constructor
1133
1134    /// Constructor.
1135    ///
1136    SmartBpGraph() {}
1137
1138    /// \brief Add a new red node to the graph.
1139    ///
1140    /// This function adds a red new node to the graph.
1141    /// \return The new node.
1142    Node addRedNode() { return Parent::addRedNode(); }
1143
1144    /// \brief Add a new blue node to the graph.
1145    ///
1146    /// This function adds a blue new node to the graph.
1147    /// \return The new node.
1148    Node addBlueNode() { return Parent::addBlueNode(); }
1149
1150    /// \brief Add a new edge to the graph.
1151    ///
1152    /// This function adds a new edge to the graph between nodes
1153    /// \c u and \c v with inherent orientation from node \c u to
1154    /// node \c v.
1155    /// \return The new edge.
1156    Edge addEdge(Node red, Node blue) {
1157      LEMON_DEBUG(Parent::red(red) && Parent::blue(blue),
1158                  "Edge has to be formed by a red and a blue nodes");
1159      return Parent::addEdge(red, blue);
1160    }
1161
1162    /// \brief Node validity check
1163    ///
1164    /// This function gives back \c true if the given node is valid,
1165    /// i.e. it is a real node of the graph.
1166    ///
1167    /// \warning A removed node (using Snapshot) could become valid again
1168    /// if new nodes are added to the graph.
1169    bool valid(Node n) const { return Parent::valid(n); }
1170
1171    /// \brief Edge validity check
1172    ///
1173    /// This function gives back \c true if the given edge is valid,
1174    /// i.e. it is a real edge of the graph.
1175    ///
1176    /// \warning A removed edge (using Snapshot) could become valid again
1177    /// if new edges are added to the graph.
1178    bool valid(Edge e) const { return Parent::valid(e); }
1179
1180    /// \brief Arc validity check
1181    ///
1182    /// This function gives back \c true if the given arc is valid,
1183    /// i.e. it is a real arc of the graph.
1184    ///
1185    /// \warning A removed arc (using Snapshot) could become valid again
1186    /// if new edges are added to the graph.
1187    bool valid(Arc a) const { return Parent::valid(a); }
1188
1189    ///Clear the graph.
1190
1191    ///This function erases all nodes and arcs from the graph.
1192    ///
1193    void clear() {
1194      Parent::clear();
1195    }
1196
1197    /// Reserve memory for nodes.
1198
1199    /// Using this function, it is possible to avoid superfluous memory
1200    /// allocation: if you know that the graph you want to build will
1201    /// be large (e.g. it will contain millions of nodes and/or edges),
1202    /// then it is worth reserving space for this amount before starting
1203    /// to build the graph.
1204    /// \sa reserveEdge()
1205    void reserveNode(int n) { nodes.reserve(n); };
1206
1207    /// Reserve memory for edges.
1208
1209    /// Using this function, it is possible to avoid superfluous memory
1210    /// allocation: if you know that the graph you want to build will
1211    /// be large (e.g. it will contain millions of nodes and/or edges),
1212    /// then it is worth reserving space for this amount before starting
1213    /// to build the graph.
1214    /// \sa reserveNode()
1215    void reserveEdge(int m) { arcs.reserve(2 * m); };
1216
1217  public:
1218
1219    class Snapshot;
1220
1221  protected:
1222
1223    void saveSnapshot(Snapshot &s)
1224    {
1225      s._graph = this;
1226      s.node_num = nodes.size();
1227      s.arc_num = arcs.size();
1228    }
1229
1230    void restoreSnapshot(const Snapshot &s)
1231    {
1232      while(s.arc_num<arcs.size()) {
1233        int n=arcs.size()-1;
1234        Edge arc=edgeFromId(n/2);
1235        Parent::notifier(Edge()).erase(arc);
1236        std::vector<Arc> dir;
1237        dir.push_back(arcFromId(n));
1238        dir.push_back(arcFromId(n-1));
1239        Parent::notifier(Arc()).erase(dir);
1240        nodes[arcs[n-1].target].first_out=arcs[n].next_out;
1241        nodes[arcs[n].target].first_out=arcs[n-1].next_out;
1242        arcs.pop_back();
1243        arcs.pop_back();
1244      }
1245      while(s.node_num<nodes.size()) {
1246        int n=nodes.size()-1;
1247        Node node = nodeFromId(n);
1248        if (Parent::red(node)) {
1249          first_red = nodes[n].partition_next;
1250          Parent::notifier(RedNode()).erase(node);         
1251        } else {
1252          first_blue = nodes[n].partition_next;
1253          Parent::notifier(BlueNode()).erase(node);
1254        }
1255        Parent::notifier(Node()).erase(node);
1256        nodes.pop_back();
1257      }
1258    }
1259
1260  public:
1261
1262    ///Class to make a snapshot of the graph and to restore it later.
1263
1264    ///Class to make a snapshot of the graph and to restore it later.
1265    ///
1266    ///The newly added nodes and edges can be removed using the
1267    ///restore() function. This is the only way for deleting nodes and/or
1268    ///edges from a SmartBpGraph structure.
1269    ///
1270    ///\note After a state is restored, you cannot restore a later state,
1271    ///i.e. you cannot add the removed nodes and edges again using
1272    ///another Snapshot instance.
1273    ///
1274    ///\warning The validity of the snapshot is not stored due to
1275    ///performance reasons. If you do not use the snapshot correctly,
1276    ///it can cause broken program, invalid or not restored state of
1277    ///the graph or no change.
1278    class Snapshot
1279    {
1280      SmartBpGraph *_graph;
1281    protected:
1282      friend class SmartBpGraph;
1283      unsigned int node_num;
1284      unsigned int arc_num;
1285    public:
1286      ///Default constructor.
1287
1288      ///Default constructor.
1289      ///You have to call save() to actually make a snapshot.
1290      Snapshot() : _graph(0) {}
1291      ///Constructor that immediately makes a snapshot
1292
1293      /// This constructor immediately makes a snapshot of the given graph.
1294      ///
1295      Snapshot(SmartBpGraph &gr) {
1296        gr.saveSnapshot(*this);
1297      }
1298
1299      ///Make a snapshot.
1300
1301      ///This function makes a snapshot of the given graph.
1302      ///It can be called more than once. In case of a repeated
1303      ///call, the previous snapshot gets lost.
1304      void save(SmartBpGraph &gr)
1305      {
1306        gr.saveSnapshot(*this);
1307      }
1308
1309      ///Undo the changes until the last snapshot.
1310
1311      ///This function undos the changes until the last snapshot
1312      ///created by save() or Snapshot(SmartBpGraph&).
1313      void restore()
1314      {
1315        _graph->restoreSnapshot(*this);
1316      }
1317    };
1318  };
1319
1320} //namespace lemon
1321
1322
1323#endif //LEMON_SMART_GRAPH_H
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