COIN-OR::LEMON - Graph Library

source: lemon/lemon/smart_graph.h @ 1191:939ee6d1e525

Last change on this file since 1191:939ee6d1e525 was 1191:939ee6d1e525, checked in by Balazs Dezso <deba@…>, 9 years ago

Use member variables to store the highest IDs in bipartite partitions (#69)

File size: 36.0 KB
Line 
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    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 Edge {
858      friend class SmartBpGraphBase;
859    protected:
860
861      int _id;
862      explicit Edge(int id) { _id = id;}
863
864    public:
865      Edge() {}
866      Edge (Invalid) { _id = -1; }
867      bool operator==(const Edge& arc) const {return _id == arc._id;}
868      bool operator!=(const Edge& arc) const {return _id != arc._id;}
869      bool operator<(const Edge& arc) const {return _id < arc._id;}
870    };
871
872    class Arc {
873      friend class SmartBpGraphBase;
874    protected:
875
876      int _id;
877      explicit Arc(int id) { _id = id;}
878
879    public:
880      operator Edge() const {
881        return _id != -1 ? edgeFromId(_id / 2) : INVALID;
882      }
883
884      Arc() {}
885      Arc (Invalid) { _id = -1; }
886      bool operator==(const Arc& arc) const {return _id == arc._id;}
887      bool operator!=(const Arc& arc) const {return _id != arc._id;}
888      bool operator<(const Arc& arc) const {return _id < arc._id;}
889    };
890
891
892
893    SmartBpGraphBase()
894      : nodes(), arcs(), first_red(-1), first_blue(-1),
895        max_red(-1), max_blue(-1) {}
896
897    typedef True NodeNumTag;
898    typedef True EdgeNumTag;
899    typedef True ArcNumTag;
900
901    int nodeNum() const { return nodes.size(); }
902    int redNum() const { return max_red + 1; }
903    int blueNum() const { return max_blue + 1; }
904    int edgeNum() const { return arcs.size() / 2; }
905    int arcNum() const { return arcs.size(); }
906
907    int maxNodeId() const { return nodes.size()-1; }
908    int maxRedId() const { return max_red; }
909    int maxBlueId() const { return max_blue; }
910    int maxEdgeId() const { return arcs.size() / 2 - 1; }
911    int maxArcId() const { return arcs.size()-1; }
912
913    bool red(Node n) const { return nodes[n._id].red; }
914    bool blue(Node n) const { return !nodes[n._id].red; }
915
916    Node source(Arc a) const { return Node(arcs[a._id ^ 1].target); }
917    Node target(Arc a) const { return Node(arcs[a._id].target); }
918
919    Node redNode(Edge e) const { return Node(arcs[2 * e._id].target); }
920    Node blueNode(Edge e) const { return Node(arcs[2 * e._id + 1].target); }
921
922    static bool direction(Arc a) {
923      return (a._id & 1) == 1;
924    }
925
926    static Arc direct(Edge e, bool d) {
927      return Arc(e._id * 2 + (d ? 1 : 0));
928    }
929
930    void first(Node& node) const {
931      node._id = nodes.size() - 1;
932    }
933
934    static void next(Node& node) {
935      --node._id;
936    }
937
938    void firstRed(Node& node) const {
939      node._id = first_red;
940    }
941
942    void nextRed(Node& node) const {
943      node._id = nodes[node._id].partition_next;
944    }
945
946    void firstBlue(Node& node) const {
947      node._id = first_blue;
948    }
949
950    void nextBlue(Node& node) const {
951      node._id = nodes[node._id].partition_next;
952    }
953
954    void first(Arc& arc) const {
955      arc._id = arcs.size() - 1;
956    }
957
958    static void next(Arc& arc) {
959      --arc._id;
960    }
961
962    void first(Edge& arc) const {
963      arc._id = arcs.size() / 2 - 1;
964    }
965
966    static void next(Edge& arc) {
967      --arc._id;
968    }
969
970    void firstOut(Arc &arc, const Node& v) const {
971      arc._id = nodes[v._id].first_out;
972    }
973    void nextOut(Arc &arc) const {
974      arc._id = arcs[arc._id].next_out;
975    }
976
977    void firstIn(Arc &arc, const Node& v) const {
978      arc._id = ((nodes[v._id].first_out) ^ 1);
979      if (arc._id == -2) arc._id = -1;
980    }
981    void nextIn(Arc &arc) const {
982      arc._id = ((arcs[arc._id ^ 1].next_out) ^ 1);
983      if (arc._id == -2) arc._id = -1;
984    }
985
986    void firstInc(Edge &arc, bool& d, const Node& v) const {
987      int de = nodes[v._id].first_out;
988      if (de != -1) {
989        arc._id = de / 2;
990        d = ((de & 1) == 1);
991      } else {
992        arc._id = -1;
993        d = true;
994      }
995    }
996    void nextInc(Edge &arc, bool& d) const {
997      int de = (arcs[(arc._id * 2) | (d ? 1 : 0)].next_out);
998      if (de != -1) {
999        arc._id = de / 2;
1000        d = ((de & 1) == 1);
1001      } else {
1002        arc._id = -1;
1003        d = true;
1004      }
1005    }
1006
1007    static int id(Node v) { return v._id; }
1008    int redId(Node v) const {
1009      LEMON_DEBUG(nodes[v._id].red, "Node has to be red");
1010      return nodes[v._id].partition_index;
1011    }
1012    int blueId(Node v) const {
1013      LEMON_DEBUG(!nodes[v._id].red, "Node has to be blue");
1014      return nodes[v._id].partition_index;
1015    }
1016    static int id(Arc e) { return e._id; }
1017    static int id(Edge e) { return e._id; }
1018
1019    static Node nodeFromId(int id) { return Node(id);}
1020    static Arc arcFromId(int id) { return Arc(id);}
1021    static Edge edgeFromId(int id) { return Edge(id);}
1022
1023    bool valid(Node n) const {
1024      return n._id >= 0 && n._id < static_cast<int>(nodes.size());
1025    }
1026    bool valid(Arc a) const {
1027      return a._id >= 0 && a._id < static_cast<int>(arcs.size());
1028    }
1029    bool valid(Edge e) const {
1030      return e._id >= 0 && 2 * e._id < static_cast<int>(arcs.size());
1031    }
1032
1033    Node addRedNode() {
1034      int n = nodes.size();
1035      nodes.push_back(NodeT());
1036      nodes[n].first_out = -1;
1037      nodes[n].red = true;
1038      nodes[n].partition_index = ++max_red;
1039      nodes[n].partition_next = first_red;
1040      first_red = n;
1041
1042      return Node(n);
1043    }
1044
1045    Node addBlueNode() {
1046      int n = nodes.size();
1047      nodes.push_back(NodeT());
1048      nodes[n].first_out = -1;
1049      nodes[n].red = false;
1050      nodes[n].partition_index = ++max_blue;
1051      nodes[n].partition_next = first_blue;
1052      first_blue = n;
1053
1054      return Node(n);
1055    }
1056
1057    Edge addEdge(Node u, Node v) {
1058      int n = arcs.size();
1059      arcs.push_back(ArcT());
1060      arcs.push_back(ArcT());
1061
1062      arcs[n].target = u._id;
1063      arcs[n | 1].target = v._id;
1064
1065      arcs[n].next_out = nodes[v._id].first_out;
1066      nodes[v._id].first_out = n;
1067
1068      arcs[n | 1].next_out = nodes[u._id].first_out;
1069      nodes[u._id].first_out = (n | 1);
1070
1071      return Edge(n / 2);
1072    }
1073
1074    void clear() {
1075      arcs.clear();
1076      nodes.clear();
1077      first_red = -1;
1078      first_blue = -1;
1079      max_blue = -1;
1080      max_red = -1;
1081    }
1082
1083  };
1084
1085  typedef BpGraphExtender<SmartBpGraphBase> ExtendedSmartBpGraphBase;
1086
1087  /// \ingroup graphs
1088  ///
1089  /// \brief A smart undirected bipartite graph class.
1090  ///
1091  /// \ref SmartBpGraph is a simple and fast bipartite graph implementation.
1092  /// It is also quite memory efficient but at the price
1093  /// that it does not support node and edge deletion
1094  /// (except for the Snapshot feature).
1095  ///
1096  /// This type fully conforms to the \ref concepts::BpGraph "BpGraph concept"
1097  /// and it also provides some additional functionalities.
1098  /// Most of its member functions and nested classes are documented
1099  /// only in the concept class.
1100  ///
1101  /// This class provides constant time counting for nodes, edges and arcs.
1102  ///
1103  /// \sa concepts::BpGraph
1104  /// \sa SmartGraph
1105  class SmartBpGraph : public ExtendedSmartBpGraphBase {
1106    typedef ExtendedSmartBpGraphBase Parent;
1107
1108  private:
1109    /// Graphs are \e not copy constructible. Use GraphCopy instead.
1110    SmartBpGraph(const SmartBpGraph &) : ExtendedSmartBpGraphBase() {};
1111    /// \brief Assignment of a graph to another one is \e not allowed.
1112    /// Use GraphCopy instead.
1113    void operator=(const SmartBpGraph &) {}
1114
1115  public:
1116
1117    /// Constructor
1118
1119    /// Constructor.
1120    ///
1121    SmartBpGraph() {}
1122
1123    /// \brief Add a new red node to the graph.
1124    ///
1125    /// This function adds a red new node to the graph.
1126    /// \return The new node.
1127    Node addRedNode() { return Parent::addRedNode(); }
1128
1129    /// \brief Add a new blue node to the graph.
1130    ///
1131    /// This function adds a blue new node to the graph.
1132    /// \return The new node.
1133    Node addBlueNode() { return Parent::addBlueNode(); }
1134
1135    /// \brief Add a new edge to the graph.
1136    ///
1137    /// This function adds a new edge to the graph between nodes
1138    /// \c u and \c v with inherent orientation from node \c u to
1139    /// node \c v.
1140    /// \return The new edge.
1141    Edge addEdge(Node red, Node blue) {
1142      LEMON_DEBUG(Parent::red(red) && Parent::blue(blue),
1143                  "Edge has to be formed by a red and a blue nodes");
1144      return Parent::addEdge(red, blue);
1145    }
1146
1147    /// \brief Node validity check
1148    ///
1149    /// This function gives back \c true if the given node is valid,
1150    /// i.e. it is a real node of the graph.
1151    ///
1152    /// \warning A removed node (using Snapshot) could become valid again
1153    /// if new nodes are added to the graph.
1154    bool valid(Node n) const { return Parent::valid(n); }
1155
1156    /// \brief Edge validity check
1157    ///
1158    /// This function gives back \c true if the given edge is valid,
1159    /// i.e. it is a real edge of the graph.
1160    ///
1161    /// \warning A removed edge (using Snapshot) could become valid again
1162    /// if new edges are added to the graph.
1163    bool valid(Edge e) const { return Parent::valid(e); }
1164
1165    /// \brief Arc validity check
1166    ///
1167    /// This function gives back \c true if the given arc is valid,
1168    /// i.e. it is a real arc of the graph.
1169    ///
1170    /// \warning A removed arc (using Snapshot) could become valid again
1171    /// if new edges are added to the graph.
1172    bool valid(Arc a) const { return Parent::valid(a); }
1173
1174    ///Clear the graph.
1175
1176    ///This function erases all nodes and arcs from the graph.
1177    ///
1178    void clear() {
1179      Parent::clear();
1180    }
1181
1182    /// Reserve memory for nodes.
1183
1184    /// Using this function, it is possible to avoid superfluous memory
1185    /// allocation: if you know that the graph you want to build will
1186    /// be large (e.g. it will contain millions of nodes and/or edges),
1187    /// then it is worth reserving space for this amount before starting
1188    /// to build the graph.
1189    /// \sa reserveEdge()
1190    void reserveNode(int n) { nodes.reserve(n); };
1191
1192    /// Reserve memory for edges.
1193
1194    /// Using this function, it is possible to avoid superfluous memory
1195    /// allocation: if you know that the graph you want to build will
1196    /// be large (e.g. it will contain millions of nodes and/or edges),
1197    /// then it is worth reserving space for this amount before starting
1198    /// to build the graph.
1199    /// \sa reserveNode()
1200    void reserveEdge(int m) { arcs.reserve(2 * m); };
1201
1202  public:
1203
1204    class Snapshot;
1205
1206  protected:
1207
1208    void saveSnapshot(Snapshot &s)
1209    {
1210      s._graph = this;
1211      s.node_num = nodes.size();
1212      s.arc_num = arcs.size();
1213    }
1214
1215    void restoreSnapshot(const Snapshot &s)
1216    {
1217      while(s.arc_num<arcs.size()) {
1218        int n=arcs.size()-1;
1219        Edge arc=edgeFromId(n/2);
1220        Parent::notifier(Edge()).erase(arc);
1221        std::vector<Arc> dir;
1222        dir.push_back(arcFromId(n));
1223        dir.push_back(arcFromId(n-1));
1224        Parent::notifier(Arc()).erase(dir);
1225        nodes[arcs[n-1].target].first_out=arcs[n].next_out;
1226        nodes[arcs[n].target].first_out=arcs[n-1].next_out;
1227        arcs.pop_back();
1228        arcs.pop_back();
1229      }
1230      while(s.node_num<nodes.size()) {
1231        int n=nodes.size()-1;
1232        Node node = nodeFromId(n);
1233        if (Parent::red(node)) {
1234          first_red = nodes[n].partition_next;
1235          if (first_red != -1) {
1236            max_red = nodes[first_red].partition_index;
1237          } else {
1238            max_red = -1;
1239          }
1240          Parent::notifier(RedNode()).erase(node);         
1241        } else {
1242          first_blue = nodes[n].partition_next;
1243          if (first_blue != -1) {
1244            max_blue = nodes[first_blue].partition_index;
1245          } else {
1246            max_blue = -1;
1247          }
1248          Parent::notifier(BlueNode()).erase(node);
1249        }
1250        Parent::notifier(Node()).erase(node);
1251        nodes.pop_back();
1252      }
1253    }
1254
1255  public:
1256
1257    ///Class to make a snapshot of the graph and to restore it later.
1258
1259    ///Class to make a snapshot of the graph and to restore it later.
1260    ///
1261    ///The newly added nodes and edges can be removed using the
1262    ///restore() function. This is the only way for deleting nodes and/or
1263    ///edges from a SmartBpGraph structure.
1264    ///
1265    ///\note After a state is restored, you cannot restore a later state,
1266    ///i.e. you cannot add the removed nodes and edges again using
1267    ///another Snapshot instance.
1268    ///
1269    ///\warning The validity of the snapshot is not stored due to
1270    ///performance reasons. If you do not use the snapshot correctly,
1271    ///it can cause broken program, invalid or not restored state of
1272    ///the graph or no change.
1273    class Snapshot
1274    {
1275      SmartBpGraph *_graph;
1276    protected:
1277      friend class SmartBpGraph;
1278      unsigned int node_num;
1279      unsigned int arc_num;
1280    public:
1281      ///Default constructor.
1282
1283      ///Default constructor.
1284      ///You have to call save() to actually make a snapshot.
1285      Snapshot() : _graph(0) {}
1286      ///Constructor that immediately makes a snapshot
1287
1288      /// This constructor immediately makes a snapshot of the given graph.
1289      ///
1290      Snapshot(SmartBpGraph &gr) {
1291        gr.saveSnapshot(*this);
1292      }
1293
1294      ///Make a snapshot.
1295
1296      ///This function makes a snapshot of the given graph.
1297      ///It can be called more than once. In case of a repeated
1298      ///call, the previous snapshot gets lost.
1299      void save(SmartBpGraph &gr)
1300      {
1301        gr.saveSnapshot(*this);
1302      }
1303
1304      ///Undo the changes until the last snapshot.
1305
1306      ///This function undos the changes until the last snapshot
1307      ///created by save() or Snapshot(SmartBpGraph&).
1308      void restore()
1309      {
1310        _graph->restoreSnapshot(*this);
1311      }
1312    };
1313  };
1314
1315} //namespace lemon
1316
1317
1318#endif //LEMON_SMART_GRAPH_H
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