COIN-OR::LEMON - Graph Library

source: lemon-0.x/lemon/list_graph.h @ 2096:dbe860a83dc9

Last change on this file since 2096:dbe860a83dc9 was 2076:10681ee9d8ae, checked in by Balazs Dezso, 14 years ago

Extenders modified

UGraphBaseExtender => UndirGraphExtender?
BpUGraphBaseExtender merged into BpUGraphExtender

File size: 25.0 KB
Line 
1/* -*- C++ -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library
4 *
5 * Copyright (C) 2003-2006
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_LIST_GRAPH_H
20#define LEMON_LIST_GRAPH_H
21
22///\ingroup graphs
23///\file
24///\brief ListGraph, ListUGraph classes.
25
26#include <lemon/bits/base_extender.h>
27#include <lemon/bits/graph_extender.h>
28
29#include <lemon/error.h>
30
31#include <vector>
32#include <list>
33
34namespace lemon {
35
36  class ListGraphBase {
37
38  protected:
39    struct NodeT {
40      int first_in, first_out;
41      int prev, next;
42    };
43 
44    struct EdgeT {
45      int target, source;
46      int prev_in, prev_out;
47      int next_in, next_out;
48    };
49
50    std::vector<NodeT> nodes;
51
52    int first_node;
53
54    int first_free_node;
55
56    std::vector<EdgeT> edges;
57
58    int first_free_edge;
59   
60  public:
61   
62    typedef ListGraphBase Graph;
63   
64    class Node {
65      friend class ListGraphBase;
66    protected:
67
68      int id;
69      explicit Node(int pid) { id = pid;}
70
71    public:
72      Node() {}
73      Node (Invalid) { id = -1; }
74      bool operator==(const Node& node) const {return id == node.id;}
75      bool operator!=(const Node& node) const {return id != node.id;}
76      bool operator<(const Node& node) const {return id < node.id;}
77    };
78
79    class Edge {
80      friend class ListGraphBase;
81    protected:
82
83      int id;
84      explicit Edge(int pid) { id = pid;}
85
86    public:
87      Edge() {}
88      Edge (Invalid) { id = -1; }
89      bool operator==(const Edge& edge) const {return id == edge.id;}
90      bool operator!=(const Edge& edge) const {return id != edge.id;}
91      bool operator<(const Edge& edge) const {return id < edge.id;}
92    };
93
94
95
96    ListGraphBase()
97      : nodes(), first_node(-1),
98        first_free_node(-1), edges(), first_free_edge(-1) {}
99
100   
101    /// Maximum node ID.
102   
103    /// Maximum node ID.
104    ///\sa id(Node)
105    int maxNodeId() const { return nodes.size()-1; }
106
107    /// Maximum edge ID.
108   
109    /// Maximum edge ID.
110    ///\sa id(Edge)
111    int maxEdgeId() const { return edges.size()-1; }
112
113    Node source(Edge e) const { return Node(edges[e.id].source); }
114    Node target(Edge e) const { return Node(edges[e.id].target); }
115
116
117    void first(Node& node) const {
118      node.id = first_node;
119    }
120
121    void next(Node& node) const {
122      node.id = nodes[node.id].next;
123    }
124
125
126    void first(Edge& e) const {
127      int n;
128      for(n = first_node;
129          n!=-1 && nodes[n].first_in == -1;
130          n = nodes[n].next);
131      e.id = (n == -1) ? -1 : nodes[n].first_in;
132    }
133
134    void next(Edge& edge) const {
135      if (edges[edge.id].next_in != -1) {
136        edge.id = edges[edge.id].next_in;
137      } else {
138        int n;
139        for(n = nodes[edges[edge.id].target].next;
140          n!=-1 && nodes[n].first_in == -1;
141          n = nodes[n].next);
142        edge.id = (n == -1) ? -1 : nodes[n].first_in;
143      }     
144    }
145
146    void firstOut(Edge &e, const Node& v) const {
147      e.id = nodes[v.id].first_out;
148    }
149    void nextOut(Edge &e) const {
150      e.id=edges[e.id].next_out;
151    }
152
153    void firstIn(Edge &e, const Node& v) const {
154      e.id = nodes[v.id].first_in;
155    }
156    void nextIn(Edge &e) const {
157      e.id=edges[e.id].next_in;
158    }
159
160   
161    static int id(Node v) { return v.id; }
162    static int id(Edge e) { return e.id; }
163
164    static Node nodeFromId(int id) { return Node(id);}
165    static Edge edgeFromId(int id) { return Edge(id);}
166
167    /// Adds a new node to the graph.
168
169    /// \warning It adds the new node to the front of the list.
170    /// (i.e. the lastly added node becomes the first.)
171    Node addNode() {     
172      int n;
173     
174      if(first_free_node==-1) {
175        n = nodes.size();
176        nodes.push_back(NodeT());
177      } else {
178        n = first_free_node;
179        first_free_node = nodes[n].next;
180      }
181     
182      nodes[n].next = first_node;
183      if(first_node != -1) nodes[first_node].prev = n;
184      first_node = n;
185      nodes[n].prev = -1;
186     
187      nodes[n].first_in = nodes[n].first_out = -1;
188     
189      return Node(n);
190    }
191   
192    Edge addEdge(Node u, Node v) {
193      int n;     
194
195      if (first_free_edge == -1) {
196        n = edges.size();
197        edges.push_back(EdgeT());
198      } else {
199        n = first_free_edge;
200        first_free_edge = edges[n].next_in;
201      }
202     
203      edges[n].source = u.id;
204      edges[n].target = v.id;
205
206      edges[n].next_out = nodes[u.id].first_out;
207      if(nodes[u.id].first_out != -1) {
208        edges[nodes[u.id].first_out].prev_out = n;
209      }
210     
211      edges[n].next_in = nodes[v.id].first_in;
212      if(nodes[v.id].first_in != -1) {
213        edges[nodes[v.id].first_in].prev_in = n;
214      }
215     
216      edges[n].prev_in = edges[n].prev_out = -1;
217       
218      nodes[u.id].first_out = nodes[v.id].first_in = n;
219
220      return Edge(n);
221    }
222   
223    void erase(const Node& node) {
224      int n = node.id;
225     
226      if(nodes[n].next != -1) {
227        nodes[nodes[n].next].prev = nodes[n].prev;
228      }
229     
230      if(nodes[n].prev != -1) {
231        nodes[nodes[n].prev].next = nodes[n].next;
232      } else {
233        first_node = nodes[n].next;
234      }
235     
236      nodes[n].next = first_free_node;
237      first_free_node = n;
238
239    }
240   
241    void erase(const Edge& edge) {
242      int n = edge.id;
243     
244      if(edges[n].next_in!=-1) {
245        edges[edges[n].next_in].prev_in = edges[n].prev_in;
246      }
247
248      if(edges[n].prev_in!=-1) {
249        edges[edges[n].prev_in].next_in = edges[n].next_in;
250      } else {
251        nodes[edges[n].target].first_in = edges[n].next_in;
252      }
253
254     
255      if(edges[n].next_out!=-1) {
256        edges[edges[n].next_out].prev_out = edges[n].prev_out;
257      }
258
259      if(edges[n].prev_out!=-1) {
260        edges[edges[n].prev_out].next_out = edges[n].next_out;
261      } else {
262        nodes[edges[n].source].first_out = edges[n].next_out;
263      }
264     
265      edges[n].next_in = first_free_edge;
266      first_free_edge = n;     
267
268    }
269
270    void clear() {
271      edges.clear();
272      nodes.clear();
273      first_node = first_free_node = first_free_edge = -1;
274    }
275
276  protected:
277    void _changeTarget(Edge e, Node n)
278    {
279      if(edges[e.id].next_in != -1)
280        edges[edges[e.id].next_in].prev_in = edges[e.id].prev_in;
281      if(edges[e.id].prev_in != -1)
282        edges[edges[e.id].prev_in].next_in = edges[e.id].next_in;
283      else nodes[edges[e.id].target].first_in = edges[e.id].next_in;
284      if (nodes[n.id].first_in != -1) {
285        edges[nodes[n.id].first_in].prev_in = e.id;
286      }
287      edges[e.id].target = n.id;
288      edges[e.id].prev_in = -1;
289      edges[e.id].next_in = nodes[n.id].first_in;
290      nodes[n.id].first_in = e.id;
291    }
292    void _changeSource(Edge e, Node n)
293    {
294      if(edges[e.id].next_out != -1)
295        edges[edges[e.id].next_out].prev_out = edges[e.id].prev_out;
296      if(edges[e.id].prev_out != -1)
297        edges[edges[e.id].prev_out].next_out = edges[e.id].next_out;
298      else nodes[edges[e.id].source].first_out = edges[e.id].next_out;
299      if (nodes[n.id].first_out != -1) {
300        edges[nodes[n.id].first_out].prev_out = e.id;
301      }
302      edges[e.id].source = n.id;
303      edges[e.id].prev_out = -1;
304      edges[e.id].next_out = nodes[n.id].first_out;
305      nodes[n.id].first_out = e.id;
306    }
307
308  };
309
310  typedef GraphExtender<ListGraphBase> ExtendedListGraphBase;
311
312  /// \addtogroup graphs
313  /// @{
314
315  ///A list graph class.
316
317  ///This is a simple and fast erasable graph implementation.
318  ///
319  ///It addition that it conforms to the
320  ///\ref concept::ErasableGraph "ErasableGraph" concept,
321  ///it also provides several additional useful extra functionalities.
322  ///\sa concept::ErasableGraph.
323
324  class ListGraph : public ExtendedListGraphBase {
325  public:
326
327    typedef ExtendedListGraphBase Parent;
328
329    /// Changes the target of \c e to \c n
330
331    /// Changes the target of \c e to \c n
332    ///
333    ///\note The <tt>Edge</tt>'s and <tt>OutEdge</tt>'s
334    ///referencing the changed edge remain
335    ///valid. However <tt>InEdge</tt>'s are invalidated.
336    void changeTarget(Edge e, Node n) {
337      _changeTarget(e,n);
338    }
339    /// Changes the source of \c e to \c n
340
341    /// Changes the source of \c e to \c n
342    ///
343    ///\note The <tt>Edge</tt>'s and <tt>InEdge</tt>'s
344    ///referencing the changed edge remain
345    ///valid. However <tt>OutEdge</tt>'s are invalidated.
346    void changeSource(Edge e, Node n) {
347      _changeSource(e,n);
348    }
349
350    /// Invert the direction of an edge.
351
352    ///\note The <tt>Edge</tt>'s
353    ///referencing the changed edge remain
354    ///valid. However <tt>OutEdge</tt>'s  and <tt>InEdge</tt>'s are invalidated.
355    void reverseEdge(Edge e) {
356      Node t=target(e);
357      _changeTarget(e,source(e));
358      _changeSource(e,t);
359    }
360
361    ///Using this it possible to avoid the superfluous memory allocation.
362
363    ///Using this it possible to avoid the superfluous memory allocation.
364    ///\todo more docs...
365    void reserveEdge(int n) { edges.reserve(n); };
366
367    ///Contract two nodes.
368
369    ///This function contracts two nodes.
370    ///
371    ///Node \p b will be removed but instead of deleting
372    ///its neighboring edges, they will be joined to \p a.
373    ///The last parameter \p r controls whether to remove loops. \c true
374    ///means that loops will be removed.
375    ///
376    ///\note The <tt>Edge</tt>s
377    ///referencing a moved edge remain
378    ///valid. However <tt>InEdge</tt>'s and <tt>OutEdge</tt>'s
379    ///may be invalidated.
380    void contract(Node a, Node b, bool r = true)
381    {
382      for(OutEdgeIt e(*this,b);e!=INVALID;) {
383        OutEdgeIt f=e;
384        ++f;
385        if(r && target(e)==a) erase(e);
386        else changeSource(e,a);
387        e=f;
388      }
389      for(InEdgeIt e(*this,b);e!=INVALID;) {
390        InEdgeIt f=e;
391        ++f;
392        if(r && source(e)==a) erase(e);
393        else changeTarget(e,a);
394        e=f;
395      }
396      erase(b);
397    }
398
399    ///Split a node.
400
401    ///This function splits a node. First a new node is added to the graph,
402    ///then the source of each outgoing edge of \c n is moved to this new node.
403    ///If \c connect is \c true (this is the default value), then a new edge
404    ///from \c n to the newly created node is also added.
405    ///\return The newly created node.
406    ///
407    ///\note The <tt>Edge</tt>s
408    ///referencing a moved edge remain
409    ///valid. However <tt>InEdge</tt>'s and <tt>OutEdge</tt>'s
410    ///may be invalidated.
411    ///\warning This functionality cannot be used together with the Snapshot
412    ///feature.
413    ///\todo It could be implemented in a bit faster way.
414    Node split(Node n, bool connect = true)
415    {
416      Node b = addNode();
417      for(OutEdgeIt e(*this,n);e!=INVALID;) {
418        OutEdgeIt f=e;
419        ++f;
420        changeSource(e,b);
421        e=f;
422      }
423      if(connect) addEdge(n,b);
424      return b;
425    }
426     
427    ///Split an edge.
428
429    ///This function splits an edge. First a new node \c b is added to the graph,
430    ///then the original edge is re-targetes to \c b. Finally an edge
431    ///from \c b to the original target is added.
432    ///\return The newly created node.
433    ///\warning This functionality cannot be used together with the Snapshot
434    ///feature.
435    Node split(Edge e)
436    {
437      Node b = addNode();
438      addEdge(b,target(e));
439      changeTarget(e,b);
440      return b;
441    }
442     
443    ///Class to make a snapshot of the graph and to restrore to it later.
444
445    ///Class to make a snapshot of the graph and to restrore to it later.
446    ///
447    ///The newly added nodes and edges can be removed using the
448    ///restore() function.
449    ///
450    ///\warning Edge and node deletions cannot be restored.
451    ///\warning Snapshots cannot be nested.
452    class Snapshot : protected Parent::NodeNotifier::ObserverBase,
453                     protected Parent::EdgeNotifier::ObserverBase
454    {
455    public:
456     
457      class UnsupportedOperation : public LogicError {
458      public:
459        virtual const char* exceptionName() const {
460          return "lemon::ListGraph::Snapshot::UnsupportedOperation";
461        }
462      };
463           
464
465    protected:
466     
467      ListGraph *g;
468      std::list<Node> added_nodes;
469      std::list<Edge> added_edges;
470     
471      bool active;
472      virtual void add(const Node& n) {
473        added_nodes.push_back(n);
474      };
475      virtual void erase(const Node&)
476      {
477        throw UnsupportedOperation();
478      }
479      virtual void add(const Edge& n) {
480        added_edges.push_back(n);
481      };
482      virtual void erase(const Edge&)
483      {
484        throw UnsupportedOperation();
485      }
486
487      ///\bug What is this used for?
488      ///
489      virtual void build() {}
490      ///\bug What is this used for?
491      ///
492      virtual void clear() {}
493
494      void regist(ListGraph &_g) {
495        g=&_g;
496        Parent::NodeNotifier::ObserverBase::attach(g->getNotifier(Node()));
497        Parent::EdgeNotifier::ObserverBase::attach(g->getNotifier(Edge()));
498      }
499           
500      void deregist() {
501        Parent::NodeNotifier::ObserverBase::detach();
502        Parent::EdgeNotifier::ObserverBase::detach();
503        g=0;
504      }
505
506    public:
507      ///Default constructur.
508     
509      ///Default constructur.
510      ///To actually make a snapshot you must call save().
511      ///
512      Snapshot() : g(0) {}
513      ///Constructor that immediately makes a snapshot.
514     
515      ///This constructor immediately makes a snapshot of the graph.
516      ///\param _g The graph we make a snapshot of.
517      Snapshot(ListGraph &_g) {
518        regist(_g);
519      }
520      ///\bug Is it necessary?
521      ///
522      ~Snapshot()
523      {
524        if(g) deregist();
525      }
526     
527      ///Make a snapshot.
528
529      ///Make a snapshot of the graph.
530      ///
531      ///This function can be called more than once. In case of a repeated
532      ///call, the previous snapshot gets lost.
533      ///\param _g The graph we make the snapshot of.
534      void save(ListGraph &_g)
535      {
536        if(g!=&_g) {
537          if(g) deregist();
538          regist(_g);
539        }
540        added_nodes.clear();
541        added_edges.clear();
542      }
543     
544    ///Undo the changes until the last snapshot.
545
546    ///Undo the changes until last snapshot created by save().
547    ///
548    ///\todo This function might be called undo().
549      void restore() {
550        ListGraph &old_g=*g;
551        deregist();
552        while(!added_edges.empty()) {
553          old_g.erase(added_edges.front());
554          added_edges.pop_front();
555        }
556        while(!added_nodes.empty()) {
557          old_g.erase(added_nodes.front());
558          added_nodes.pop_front();
559        }
560      }
561    };
562   
563  };
564
565  ///@}
566
567  /**************** Undirected List Graph ****************/
568
569  typedef UGraphExtender<UndirGraphExtender<ListGraphBase> >
570  ExtendedListUGraphBase;
571
572  /// \addtogroup graphs
573  /// @{
574
575  ///An undirected list graph class.
576
577  ///This is a simple and fast erasable undirected graph implementation.
578  ///
579  ///It conforms to the
580  ///\ref concept::UGraph "UGraph" concept.
581  ///
582  ///\sa concept::UGraph.
583  ///
584  ///\todo Snapshot, reverseEdge(), changeTarget(), changeSource(), contract()
585  ///haven't been implemented yet.
586  ///
587  class ListUGraph : public ExtendedListUGraphBase {
588  public:
589    typedef ExtendedListUGraphBase Parent;
590    /// \brief Changes the target of \c e to \c n
591    ///
592    /// Changes the target of \c e to \c n
593    ///
594    /// \note The <tt>Edge</tt>'s and <tt>OutEdge</tt>'s
595    /// referencing the changed edge remain
596    /// valid. However <tt>InEdge</tt>'s are invalidated.
597    void changeTarget(UEdge e, Node n) {
598      _changeTarget(e,n);
599    }
600    /// Changes the source of \c e to \c n
601    ///
602    /// Changes the source of \c e to \c n
603    ///
604    ///\note The <tt>Edge</tt>'s and <tt>InEdge</tt>'s
605    ///referencing the changed edge remain
606    ///valid. However <tt>OutEdge</tt>'s are invalidated.
607    void changeSource(UEdge e, Node n) {
608      _changeSource(e,n);
609    }
610    /// \brief Contract two nodes.
611    ///
612    /// This function contracts two nodes.
613    ///
614    /// Node \p b will be removed but instead of deleting
615    /// its neighboring edges, they will be joined to \p a.
616    /// The last parameter \p r controls whether to remove loops. \c true
617    /// means that loops will be removed.
618    ///
619    /// \note The <tt>Edge</tt>s
620    /// referencing a moved edge remain
621    /// valid.
622    void contract(Node a, Node b, bool r = true) {
623      for(IncEdgeIt e(*this, b); e!=INVALID;) {
624        IncEdgeIt f = e; ++f;
625        if (r && runningNode(e) == a) {
626          erase(e);
627        } else if (source(e) == b) {
628          changeSource(e, a);
629        } else {
630          changeTarget(e, a);
631        }
632        e = f;
633      }
634      erase(b);
635    }
636  };
637
638
639  class ListBpUGraphBase {
640  public:
641
642    class NodeSetError : public LogicError {
643      virtual const char* exceptionName() const {
644        return "lemon::ListBpUGraph::NodeSetError";
645      }
646    };
647
648  protected:
649
650    struct NodeT {
651      int first_edge, next_node;
652    };
653
654    struct UEdgeT {
655      int aNode, prev_out, next_out;
656      int bNode, prev_in, next_in;
657    };
658
659    std::vector<NodeT> aNodes;
660    std::vector<NodeT> bNodes;
661
662    std::vector<UEdgeT> edges;
663
664    int first_anode;
665    int first_free_anode;
666
667    int first_bnode;
668    int first_free_bnode;
669
670    int first_free_edge;
671
672  public:
673 
674    class Node {
675      friend class ListBpUGraphBase;
676    protected:
677      int id;
678
679      explicit Node(int _id) : id(_id) {}
680    public:
681      Node() {}
682      Node(Invalid) { id = -1; }
683      bool operator==(const Node i) const {return id==i.id;}
684      bool operator!=(const Node i) const {return id!=i.id;}
685      bool operator<(const Node i) const {return id<i.id;}
686    };
687
688    class UEdge {
689      friend class ListBpUGraphBase;
690    protected:
691      int id;
692
693      explicit UEdge(int _id) { id = _id;}
694    public:
695      UEdge() {}
696      UEdge (Invalid) { id = -1; }
697      bool operator==(const UEdge i) const {return id==i.id;}
698      bool operator!=(const UEdge i) const {return id!=i.id;}
699      bool operator<(const UEdge i) const {return id<i.id;}
700    };
701
702    ListBpUGraphBase()
703      : first_anode(-1), first_free_anode(-1),
704        first_bnode(-1), first_free_bnode(-1),
705        first_free_edge(-1) {}
706
707    void firstANode(Node& node) const {
708      node.id = first_anode != -1 ? (first_anode << 1) : -1;
709    }
710    void nextANode(Node& node) const {
711      node.id = aNodes[node.id >> 1].next_node;
712    }
713
714    void firstBNode(Node& node) const {
715      node.id =  first_bnode != -1 ? (first_bnode << 1) + 1 : -1;
716    }
717    void nextBNode(Node& node) const {
718      node.id = bNodes[node.id >> 1].next_node;
719    }
720
721    void first(Node& node) const {
722      if (first_anode != -1) {
723        node.id = (first_anode << 1);
724      } else if (first_bnode != -1) {
725        node.id = (first_bnode << 1) + 1;
726      } else {
727        node.id = -1;
728      }
729    }
730    void next(Node& node) const {
731      if (aNode(node)) {
732        node.id = aNodes[node.id >> 1].next_node;
733        if (node.id == -1) {
734          if (first_bnode != -1) {
735            node.id = (first_bnode << 1) + 1;
736          }
737        }
738      } else {
739        node.id = bNodes[node.id >> 1].next_node;
740      }
741    }
742 
743    void first(UEdge& edge) const {
744      int aNodeId = first_anode;
745      while (aNodeId != -1 && aNodes[aNodeId].first_edge == -1) {
746        aNodeId = aNodes[aNodeId].next_node != -1 ?
747          aNodes[aNodeId].next_node >> 1 : -1;
748      }
749      if (aNodeId != -1) {
750        edge.id = aNodes[aNodeId].first_edge;
751      } else {
752        edge.id = -1;
753      }
754    }
755    void next(UEdge& edge) const {
756      int aNodeId = edges[edge.id].aNode >> 1;
757      edge.id = edges[edge.id].next_out;
758      if (edge.id == -1) {
759        aNodeId = aNodes[aNodeId].next_node != -1 ?
760          aNodes[aNodeId].next_node >> 1 : -1;
761        while (aNodeId != -1 && aNodes[aNodeId].first_edge == -1) {
762          aNodeId = aNodes[aNodeId].next_node != -1 ?
763          aNodes[aNodeId].next_node >> 1 : -1;
764        }
765        if (aNodeId != -1) {
766          edge.id = aNodes[aNodeId].first_edge;
767        } else {
768          edge.id = -1;
769        }
770      }
771    }
772
773    void firstFromANode(UEdge& edge, const Node& node) const {
774      LEMON_ASSERT((node.id & 1) == 0, NodeSetError());
775      edge.id = aNodes[node.id >> 1].first_edge;
776    }
777    void nextFromANode(UEdge& edge) const {
778      edge.id = edges[edge.id].next_out;
779    }
780
781    void firstFromBNode(UEdge& edge, const Node& node) const {
782      LEMON_ASSERT((node.id & 1) == 1, NodeSetError());
783      edge.id = bNodes[node.id >> 1].first_edge;
784    }
785    void nextFromBNode(UEdge& edge) const {
786      edge.id = edges[edge.id].next_in;
787    }
788
789    static int id(const Node& node) {
790      return node.id;
791    }
792    static Node nodeFromId(int id) {
793      return Node(id);
794    }
795    int maxNodeId() const {
796      return aNodes.size() > bNodes.size() ?
797        aNodes.size() * 2 - 2 : bNodes.size() * 2 - 1;
798    }
799 
800    static int id(const UEdge& edge) {
801      return edge.id;
802    }
803    static UEdge uEdgeFromId(int id) {
804      return UEdge(id);
805    }
806    int maxUEdgeId() const {
807      return edges.size();
808    }
809 
810    static int aNodeId(const Node& node) {
811      return node.id >> 1;
812    }
813    static Node fromANodeId(int id) {
814      return Node(id << 1);
815    }
816    int maxANodeId() const {
817      return aNodes.size();
818    }
819
820    static int bNodeId(const Node& node) {
821      return node.id >> 1;
822    }
823    static Node fromBNodeId(int id) {
824      return Node((id << 1) + 1);
825    }
826    int maxBNodeId() const {
827      return bNodes.size();
828    }
829
830    Node aNode(const UEdge& edge) const {
831      return Node(edges[edge.id].aNode);
832    }
833    Node bNode(const UEdge& edge) const {
834      return Node(edges[edge.id].bNode);
835    }
836
837    static bool aNode(const Node& node) {
838      return (node.id & 1) == 0;
839    }
840
841    static bool bNode(const Node& node) {
842      return (node.id & 1) == 1;
843    }
844
845    Node addANode() {
846      int aNodeId;
847      if (first_free_anode == -1) {
848        aNodeId = aNodes.size();
849        aNodes.push_back(NodeT());
850      } else {
851        aNodeId = first_free_anode;
852        first_free_anode = aNodes[first_free_anode].next_node;
853      }
854      aNodes[aNodeId].next_node =
855        first_anode != -1 ? (first_anode << 1) : -1;
856      first_anode = aNodeId;
857      aNodes[aNodeId].first_edge = -1;
858      return Node(aNodeId << 1);
859    }
860
861    Node addBNode() {
862      int bNodeId;
863      if (first_free_bnode == -1) {
864        bNodeId = bNodes.size();
865        bNodes.push_back(NodeT());
866      } else {
867        bNodeId = first_free_bnode;
868        first_free_bnode = bNodes[first_free_bnode].next_node;
869      }
870      bNodes[bNodeId].next_node =
871        first_bnode != -1 ? (first_bnode << 1) + 1 : -1;
872      first_bnode = bNodeId;
873      bNodes[bNodeId].first_edge = -1;
874      return Node((bNodeId << 1) + 1);
875    }
876
877    UEdge addEdge(const Node& source, const Node& target) {
878      LEMON_ASSERT(((source.id ^ target.id) & 1) == 1, NodeSetError());
879      int edgeId;
880      if (first_free_edge != -1) {
881        edgeId = first_free_edge;
882        first_free_edge = edges[edgeId].next_out;
883      } else {
884        edgeId = edges.size();
885        edges.push_back(UEdgeT());
886      }
887      if ((source.id & 1) == 0) {
888        edges[edgeId].aNode = source.id;
889        edges[edgeId].bNode = target.id;
890      } else {
891        edges[edgeId].aNode = target.id;
892        edges[edgeId].bNode = source.id;
893      }
894      edges[edgeId].next_out = aNodes[edges[edgeId].aNode >> 1].first_edge;
895      edges[edgeId].prev_out = -1;
896      if (aNodes[edges[edgeId].aNode >> 1].first_edge != -1) {
897        edges[aNodes[edges[edgeId].aNode >> 1].first_edge].prev_out = edgeId;
898      }
899      aNodes[edges[edgeId].aNode >> 1].first_edge = edgeId;
900      edges[edgeId].next_in = bNodes[edges[edgeId].bNode >> 1].first_edge;
901      edges[edgeId].prev_in = -1;
902      if (bNodes[edges[edgeId].bNode >> 1].first_edge != -1) {
903        edges[bNodes[edges[edgeId].bNode >> 1].first_edge].prev_in = edgeId;
904      }
905      bNodes[edges[edgeId].bNode >> 1].first_edge = edgeId;
906      return UEdge(edgeId);
907    }
908
909    void erase(const Node& node) {
910      if (aNode(node)) {
911        int aNodeId = node.id >> 1;
912        aNodes[aNodeId].next_node = first_free_anode;
913        first_free_anode = aNodeId;
914      } else {
915        int bNodeId = node.id >> 1;
916        bNodes[bNodeId].next_node = first_free_bnode;
917        first_free_bnode = bNodeId;
918      }
919    }
920
921    void erase(const UEdge& edge) {
922      if (edges[edge.id].prev_out != -1) {
923        edges[edges[edge.id].prev_out].next_out = edges[edge.id].next_out;
924      } else {
925        aNodes[edges[edge.id].aNode].first_edge = edges[edge.id].next_out;
926      }
927      if (edges[edge.id].next_out != -1) {
928        edges[edges[edge.id].next_out].prev_out = edges[edge.id].prev_out;
929      }
930      if (edges[edge.id].prev_in != -1) {
931        edges[edges[edge.id].prev_in].next_in = edges[edge.id].next_in;
932      } else {
933        bNodes[edges[edge.id].bNode].first_edge = edges[edge.id].next_in;
934      }
935      if (edges[edge.id].next_in != -1) {
936        edges[edges[edge.id].next_in].prev_in = edges[edge.id].prev_in;
937      }
938      edges[edge.id].next_out = first_free_edge;
939      first_free_edge = edge.id;
940    }
941
942    void clear() {
943      aNodes.clear();
944      bNodes.clear();
945      edges.clear();
946      first_anode = -1;
947      first_free_anode = -1;
948      first_bnode = -1;
949      first_free_bnode = -1;
950      first_free_edge = -1;
951    }
952
953  };
954
955
956  typedef BpUGraphExtender< ListBpUGraphBase > ExtendedListBpUGraphBase;
957
958  /// \ingroup graphs
959  ///
960  /// \brief A smart bipartite undirected graph class.
961  ///
962  /// This is a bipartite undirected graph implementation.
963  /// It is conforms to the \ref concept::ErasableBpUGraph "ErasableBpUGraph"
964  /// concept.
965  /// \sa concept::BpUGraph.
966  ///
967  class ListBpUGraph : public ExtendedListBpUGraphBase {};
968
969 
970  /// @} 
971} //namespace lemon
972 
973
974#endif
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