COIN-OR::LEMON - Graph Library

source: lemon/lemon/smart_graph.h @ 1270:dceba191c00d

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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) 2003-2013
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    int max_red, max_blue;
833
834  public:
835
836    typedef SmartBpGraphBase Graph;
837
838    class Node;
839    class Arc;
840    class Edge;
841
842    class Node {
843      friend class SmartBpGraphBase;
844    protected:
845
846      int _id;
847      explicit Node(int id) { _id = id;}
848
849    public:
850      Node() {}
851      Node (Invalid) { _id = -1; }
852      bool operator==(const Node& node) const {return _id == node._id;}
853      bool operator!=(const Node& node) const {return _id != node._id;}
854      bool operator<(const Node& node) const {return _id < node._id;}
855    };
856
857    class RedNode : public Node {
858      friend class SmartBpGraphBase;
859    protected:
860
861      explicit RedNode(int pid) : Node(pid) {}
862
863    public:
864      RedNode() {}
865      RedNode(const RedNode& node) : Node(node) {}
866      RedNode(Invalid) : Node(INVALID){}
867    };
868
869    class BlueNode : public Node {
870      friend class SmartBpGraphBase;
871    protected:
872
873      explicit BlueNode(int pid) : Node(pid) {}
874
875    public:
876      BlueNode() {}
877      BlueNode(const BlueNode& node) : Node(node) {}
878      BlueNode(Invalid) : Node(INVALID){}
879    };
880
881    class Edge {
882      friend class SmartBpGraphBase;
883    protected:
884
885      int _id;
886      explicit Edge(int id) { _id = id;}
887
888    public:
889      Edge() {}
890      Edge (Invalid) { _id = -1; }
891      bool operator==(const Edge& arc) const {return _id == arc._id;}
892      bool operator!=(const Edge& arc) const {return _id != arc._id;}
893      bool operator<(const Edge& arc) const {return _id < arc._id;}
894    };
895
896    class Arc {
897      friend class SmartBpGraphBase;
898    protected:
899
900      int _id;
901      explicit Arc(int id) { _id = id;}
902
903    public:
904      operator Edge() const {
905        return _id != -1 ? edgeFromId(_id / 2) : INVALID;
906      }
907
908      Arc() {}
909      Arc (Invalid) { _id = -1; }
910      bool operator==(const Arc& arc) const {return _id == arc._id;}
911      bool operator!=(const Arc& arc) const {return _id != arc._id;}
912      bool operator<(const Arc& arc) const {return _id < arc._id;}
913    };
914
915
916
917    SmartBpGraphBase()
918      : nodes(), arcs(), first_red(-1), first_blue(-1),
919        max_red(-1), max_blue(-1) {}
920
921    typedef True NodeNumTag;
922    typedef True EdgeNumTag;
923    typedef True ArcNumTag;
924
925    int nodeNum() const { return nodes.size(); }
926    int redNum() const { return max_red + 1; }
927    int blueNum() const { return max_blue + 1; }
928    int edgeNum() const { return arcs.size() / 2; }
929    int arcNum() const { return arcs.size(); }
930
931    int maxNodeId() const { return nodes.size()-1; }
932    int maxRedId() const { return max_red; }
933    int maxBlueId() const { return max_blue; }
934    int maxEdgeId() const { return arcs.size() / 2 - 1; }
935    int maxArcId() const { return arcs.size()-1; }
936
937    bool red(Node n) const { return nodes[n._id].red; }
938    bool blue(Node n) const { return !nodes[n._id].red; }
939
940    static RedNode asRedNodeUnsafe(Node n) { return RedNode(n._id); }
941    static BlueNode asBlueNodeUnsafe(Node n) { return BlueNode(n._id); }
942
943    Node source(Arc a) const { return Node(arcs[a._id ^ 1].target); }
944    Node target(Arc a) const { return Node(arcs[a._id].target); }
945
946    RedNode redNode(Edge e) const {
947      return RedNode(arcs[2 * e._id].target);
948    }
949    BlueNode blueNode(Edge e) const {
950      return BlueNode(arcs[2 * e._id + 1].target);
951    }
952
953    static bool direction(Arc a) {
954      return (a._id & 1) == 1;
955    }
956
957    static Arc direct(Edge e, bool d) {
958      return Arc(e._id * 2 + (d ? 1 : 0));
959    }
960
961    void first(Node& node) const {
962      node._id = nodes.size() - 1;
963    }
964
965    static void next(Node& node) {
966      --node._id;
967    }
968
969    void first(RedNode& node) const {
970      node._id = first_red;
971    }
972
973    void next(RedNode& node) const {
974      node._id = nodes[node._id].partition_next;
975    }
976
977    void first(BlueNode& node) const {
978      node._id = first_blue;
979    }
980
981    void next(BlueNode& node) const {
982      node._id = nodes[node._id].partition_next;
983    }
984
985    void first(Arc& arc) const {
986      arc._id = arcs.size() - 1;
987    }
988
989    static void next(Arc& arc) {
990      --arc._id;
991    }
992
993    void first(Edge& arc) const {
994      arc._id = arcs.size() / 2 - 1;
995    }
996
997    static void next(Edge& arc) {
998      --arc._id;
999    }
1000
1001    void firstOut(Arc &arc, const Node& v) const {
1002      arc._id = nodes[v._id].first_out;
1003    }
1004    void nextOut(Arc &arc) const {
1005      arc._id = arcs[arc._id].next_out;
1006    }
1007
1008    void firstIn(Arc &arc, const Node& v) const {
1009      arc._id = ((nodes[v._id].first_out) ^ 1);
1010      if (arc._id == -2) arc._id = -1;
1011    }
1012    void nextIn(Arc &arc) const {
1013      arc._id = ((arcs[arc._id ^ 1].next_out) ^ 1);
1014      if (arc._id == -2) arc._id = -1;
1015    }
1016
1017    void firstInc(Edge &arc, bool& d, const Node& v) const {
1018      int de = nodes[v._id].first_out;
1019      if (de != -1) {
1020        arc._id = de / 2;
1021        d = ((de & 1) == 1);
1022      } else {
1023        arc._id = -1;
1024        d = true;
1025      }
1026    }
1027    void nextInc(Edge &arc, bool& d) const {
1028      int de = (arcs[(arc._id * 2) | (d ? 1 : 0)].next_out);
1029      if (de != -1) {
1030        arc._id = de / 2;
1031        d = ((de & 1) == 1);
1032      } else {
1033        arc._id = -1;
1034        d = true;
1035      }
1036    }
1037
1038    static int id(Node v) { return v._id; }
1039    int id(RedNode v) const { return nodes[v._id].partition_index; }
1040    int id(BlueNode v) const { return nodes[v._id].partition_index; }
1041    static int id(Arc e) { return e._id; }
1042    static int id(Edge e) { return e._id; }
1043
1044    static Node nodeFromId(int id) { return Node(id);}
1045    static Arc arcFromId(int id) { return Arc(id);}
1046    static Edge edgeFromId(int id) { return Edge(id);}
1047
1048    bool valid(Node n) const {
1049      return n._id >= 0 && n._id < static_cast<int>(nodes.size());
1050    }
1051    bool valid(Arc a) const {
1052      return a._id >= 0 && a._id < static_cast<int>(arcs.size());
1053    }
1054    bool valid(Edge e) const {
1055      return e._id >= 0 && 2 * e._id < static_cast<int>(arcs.size());
1056    }
1057
1058    RedNode addRedNode() {
1059      int n = nodes.size();
1060      nodes.push_back(NodeT());
1061      nodes[n].first_out = -1;
1062      nodes[n].red = true;
1063      nodes[n].partition_index = ++max_red;
1064      nodes[n].partition_next = first_red;
1065      first_red = n;
1066
1067      return RedNode(n);
1068    }
1069
1070    BlueNode addBlueNode() {
1071      int n = nodes.size();
1072      nodes.push_back(NodeT());
1073      nodes[n].first_out = -1;
1074      nodes[n].red = false;
1075      nodes[n].partition_index = ++max_blue;
1076      nodes[n].partition_next = first_blue;
1077      first_blue = n;
1078
1079      return BlueNode(n);
1080    }
1081
1082    Edge addEdge(RedNode u, BlueNode v) {
1083      int n = arcs.size();
1084      arcs.push_back(ArcT());
1085      arcs.push_back(ArcT());
1086
1087      arcs[n].target = u._id;
1088      arcs[n | 1].target = v._id;
1089
1090      arcs[n].next_out = nodes[v._id].first_out;
1091      nodes[v._id].first_out = n;
1092
1093      arcs[n | 1].next_out = nodes[u._id].first_out;
1094      nodes[u._id].first_out = (n | 1);
1095
1096      return Edge(n / 2);
1097    }
1098
1099    void clear() {
1100      arcs.clear();
1101      nodes.clear();
1102      first_red = -1;
1103      first_blue = -1;
1104      max_blue = -1;
1105      max_red = -1;
1106    }
1107
1108  };
1109
1110  typedef BpGraphExtender<SmartBpGraphBase> ExtendedSmartBpGraphBase;
1111
1112  /// \ingroup graphs
1113  ///
1114  /// \brief A smart undirected bipartite graph class.
1115  ///
1116  /// \ref SmartBpGraph is a simple and fast bipartite graph implementation.
1117  /// It is also quite memory efficient but at the price
1118  /// that it does not support node and edge deletion
1119  /// (except for the Snapshot feature).
1120  ///
1121  /// This type fully conforms to the \ref concepts::BpGraph "BpGraph concept"
1122  /// and it also provides some additional functionalities.
1123  /// Most of its member functions and nested classes are documented
1124  /// only in the concept class.
1125  ///
1126  /// This class provides constant time counting for nodes, edges and arcs.
1127  ///
1128  /// \sa concepts::BpGraph
1129  /// \sa SmartGraph
1130  class SmartBpGraph : public ExtendedSmartBpGraphBase {
1131    typedef ExtendedSmartBpGraphBase Parent;
1132
1133  private:
1134    /// Graphs are \e not copy constructible. Use GraphCopy instead.
1135    SmartBpGraph(const SmartBpGraph &) : ExtendedSmartBpGraphBase() {};
1136    /// \brief Assignment of a graph to another one is \e not allowed.
1137    /// Use GraphCopy instead.
1138    void operator=(const SmartBpGraph &) {}
1139
1140  public:
1141
1142    /// Constructor
1143
1144    /// Constructor.
1145    ///
1146    SmartBpGraph() {}
1147
1148    /// \brief Add a new red node to the graph.
1149    ///
1150    /// This function adds a red new node to the graph.
1151    /// \return The new node.
1152    RedNode addRedNode() { return Parent::addRedNode(); }
1153
1154    /// \brief Add a new blue node to the graph.
1155    ///
1156    /// This function adds a blue new node to the graph.
1157    /// \return The new node.
1158    BlueNode addBlueNode() { return Parent::addBlueNode(); }
1159
1160    /// \brief Add a new edge to the graph.
1161    ///
1162    /// This function adds a new edge to the graph between nodes
1163    /// \c u and \c v with inherent orientation from node \c u to
1164    /// node \c v.
1165    /// \return The new edge.
1166    Edge addEdge(RedNode u, BlueNode v) {
1167      return Parent::addEdge(u, v);
1168    }
1169    Edge addEdge(BlueNode v, RedNode u) {
1170      return Parent::addEdge(u, v);
1171    }
1172
1173    /// \brief Node validity check
1174    ///
1175    /// This function gives back \c true if the given node is valid,
1176    /// i.e. it is a real node of the graph.
1177    ///
1178    /// \warning A removed node (using Snapshot) could become valid again
1179    /// if new nodes are added to the graph.
1180    bool valid(Node n) const { return Parent::valid(n); }
1181
1182    /// \brief Edge validity check
1183    ///
1184    /// This function gives back \c true if the given edge is valid,
1185    /// i.e. it is a real edge of the graph.
1186    ///
1187    /// \warning A removed edge (using Snapshot) could become valid again
1188    /// if new edges are added to the graph.
1189    bool valid(Edge e) const { return Parent::valid(e); }
1190
1191    /// \brief Arc validity check
1192    ///
1193    /// This function gives back \c true if the given arc is valid,
1194    /// i.e. it is a real arc of the graph.
1195    ///
1196    /// \warning A removed arc (using Snapshot) could become valid again
1197    /// if new edges are added to the graph.
1198    bool valid(Arc a) const { return Parent::valid(a); }
1199
1200    ///Clear the graph.
1201
1202    ///This function erases all nodes and arcs from the graph.
1203    ///
1204    void clear() {
1205      Parent::clear();
1206    }
1207
1208    /// Reserve memory for nodes.
1209
1210    /// Using this function, it is possible to avoid superfluous memory
1211    /// allocation: if you know that the graph you want to build will
1212    /// be large (e.g. it will contain millions of nodes and/or edges),
1213    /// then it is worth reserving space for this amount before starting
1214    /// to build the graph.
1215    /// \sa reserveEdge()
1216    void reserveNode(int n) { nodes.reserve(n); };
1217
1218    /// Reserve memory for edges.
1219
1220    /// Using this function, it is possible to avoid superfluous memory
1221    /// allocation: if you know that the graph you want to build will
1222    /// be large (e.g. it will contain millions of nodes and/or edges),
1223    /// then it is worth reserving space for this amount before starting
1224    /// to build the graph.
1225    /// \sa reserveNode()
1226    void reserveEdge(int m) { arcs.reserve(2 * m); };
1227
1228  public:
1229
1230    class Snapshot;
1231
1232  protected:
1233
1234    void saveSnapshot(Snapshot &s)
1235    {
1236      s._graph = this;
1237      s.node_num = nodes.size();
1238      s.arc_num = arcs.size();
1239    }
1240
1241    void restoreSnapshot(const Snapshot &s)
1242    {
1243      while(s.arc_num<arcs.size()) {
1244        int n=arcs.size()-1;
1245        Edge arc=edgeFromId(n/2);
1246        Parent::notifier(Edge()).erase(arc);
1247        std::vector<Arc> dir;
1248        dir.push_back(arcFromId(n));
1249        dir.push_back(arcFromId(n-1));
1250        Parent::notifier(Arc()).erase(dir);
1251        nodes[arcs[n-1].target].first_out=arcs[n].next_out;
1252        nodes[arcs[n].target].first_out=arcs[n-1].next_out;
1253        arcs.pop_back();
1254        arcs.pop_back();
1255      }
1256      while(s.node_num<nodes.size()) {
1257        int n=nodes.size()-1;
1258        Node node = nodeFromId(n);
1259        if (Parent::red(node)) {
1260          first_red = nodes[n].partition_next;
1261          if (first_red != -1) {
1262            max_red = nodes[first_red].partition_index;
1263          } else {
1264            max_red = -1;
1265          }
1266          Parent::notifier(RedNode()).erase(asRedNodeUnsafe(node));
1267        } else {
1268          first_blue = nodes[n].partition_next;
1269          if (first_blue != -1) {
1270            max_blue = nodes[first_blue].partition_index;
1271          } else {
1272            max_blue = -1;
1273          }
1274          Parent::notifier(BlueNode()).erase(asBlueNodeUnsafe(node));
1275        }
1276        Parent::notifier(Node()).erase(node);
1277        nodes.pop_back();
1278      }
1279    }
1280
1281  public:
1282
1283    ///Class to make a snapshot of the graph and to restore it later.
1284
1285    ///Class to make a snapshot of the graph and to restore it later.
1286    ///
1287    ///The newly added nodes and edges can be removed using the
1288    ///restore() function. This is the only way for deleting nodes and/or
1289    ///edges from a SmartBpGraph structure.
1290    ///
1291    ///\note After a state is restored, you cannot restore a later state,
1292    ///i.e. you cannot add the removed nodes and edges again using
1293    ///another Snapshot instance.
1294    ///
1295    ///\warning The validity of the snapshot is not stored due to
1296    ///performance reasons. If you do not use the snapshot correctly,
1297    ///it can cause broken program, invalid or not restored state of
1298    ///the graph or no change.
1299    class Snapshot
1300    {
1301      SmartBpGraph *_graph;
1302    protected:
1303      friend class SmartBpGraph;
1304      unsigned int node_num;
1305      unsigned int arc_num;
1306    public:
1307      ///Default constructor.
1308
1309      ///Default constructor.
1310      ///You have to call save() to actually make a snapshot.
1311      Snapshot() : _graph(0) {}
1312      ///Constructor that immediately makes a snapshot
1313
1314      /// This constructor immediately makes a snapshot of the given graph.
1315      ///
1316      Snapshot(SmartBpGraph &gr) {
1317        gr.saveSnapshot(*this);
1318      }
1319
1320      ///Make a snapshot.
1321
1322      ///This function makes a snapshot of the given graph.
1323      ///It can be called more than once. In case of a repeated
1324      ///call, the previous snapshot gets lost.
1325      void save(SmartBpGraph &gr)
1326      {
1327        gr.saveSnapshot(*this);
1328      }
1329
1330      ///Undo the changes until the last snapshot.
1331
1332      ///This function undos the changes until the last snapshot
1333      ///created by save() or Snapshot(SmartBpGraph&).
1334      void restore()
1335      {
1336        _graph->restoreSnapshot(*this);
1337      }
1338    };
1339  };
1340
1341} //namespace lemon
1342
1343
1344#endif //LEMON_SMART_GRAPH_H
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