alpar@209: /* -*- mode: C++; indent-tabs-mode: nil; -*-
alpar@39:  *
alpar@209:  * This file is a part of LEMON, a generic C++ optimization library.
alpar@39:  *
alpar@440:  * Copyright (C) 2003-2009
alpar@39:  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
alpar@39:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
alpar@39:  *
alpar@39:  * Permission to use, modify and distribute this software is granted
alpar@39:  * provided that this copyright notice appears in all copies. For
alpar@39:  * precise terms see the accompanying LICENSE file.
alpar@39:  *
alpar@39:  * This software is provided "AS IS" with no warranty of any kind,
alpar@39:  * express or implied, and with no claim as to its suitability for any
alpar@39:  * purpose.
alpar@39:  *
alpar@39:  */
alpar@39: 
deba@57: #ifndef LEMON_LIST_GRAPH_H
deba@57: #define LEMON_LIST_GRAPH_H
deba@57: 
deba@57: ///\ingroup graphs
deba@57: ///\file
kpeter@735: ///\brief ListDigraph and ListGraph classes.
deba@57: 
deba@220: #include <lemon/core.h>
deba@220: #include <lemon/error.h>
deba@57: #include <lemon/bits/graph_extender.h>
deba@57: 
deba@57: #include <vector>
deba@57: #include <list>
deba@57: 
deba@57: namespace lemon {
deba@57: 
kpeter@738:   class ListDigraph;
kpeter@738: 
deba@57:   class ListDigraphBase {
deba@57: 
deba@57:   protected:
deba@57:     struct NodeT {
deba@57:       int first_in, first_out;
deba@57:       int prev, next;
deba@57:     };
alpar@209: 
deba@57:     struct ArcT {
deba@57:       int target, source;
deba@57:       int prev_in, prev_out;
deba@57:       int next_in, next_out;
deba@57:     };
deba@57: 
deba@57:     std::vector<NodeT> nodes;
deba@57: 
deba@57:     int first_node;
deba@57: 
deba@57:     int first_free_node;
deba@57: 
deba@57:     std::vector<ArcT> arcs;
deba@57: 
deba@57:     int first_free_arc;
alpar@209: 
deba@57:   public:
alpar@209: 
deba@57:     typedef ListDigraphBase Digraph;
alpar@209: 
deba@57:     class Node {
deba@57:       friend class ListDigraphBase;
kpeter@738:       friend class ListDigraph;
deba@57:     protected:
deba@57: 
deba@57:       int id;
deba@57:       explicit Node(int pid) { id = pid;}
deba@57: 
deba@57:     public:
deba@57:       Node() {}
deba@57:       Node (Invalid) { id = -1; }
deba@57:       bool operator==(const Node& node) const {return id == node.id;}
deba@57:       bool operator!=(const Node& node) const {return id != node.id;}
deba@57:       bool operator<(const Node& node) const {return id < node.id;}
deba@57:     };
deba@57: 
deba@57:     class Arc {
deba@57:       friend class ListDigraphBase;
kpeter@738:       friend class ListDigraph;
deba@57:     protected:
deba@57: 
deba@57:       int id;
deba@57:       explicit Arc(int pid) { id = pid;}
deba@57: 
deba@57:     public:
deba@57:       Arc() {}
deba@57:       Arc (Invalid) { id = -1; }
deba@57:       bool operator==(const Arc& arc) const {return id == arc.id;}
deba@57:       bool operator!=(const Arc& arc) const {return id != arc.id;}
deba@57:       bool operator<(const Arc& arc) const {return id < arc.id;}
deba@57:     };
deba@57: 
deba@57: 
deba@57: 
deba@57:     ListDigraphBase()
deba@57:       : nodes(), first_node(-1),
alpar@209:         first_free_node(-1), arcs(), first_free_arc(-1) {}
deba@57: 
alpar@209: 
alpar@209:     int maxNodeId() const { return nodes.size()-1; }
deba@57:     int maxArcId() const { return arcs.size()-1; }
deba@57: 
deba@57:     Node source(Arc e) const { return Node(arcs[e.id].source); }
deba@57:     Node target(Arc e) const { return Node(arcs[e.id].target); }
deba@57: 
deba@57: 
alpar@209:     void first(Node& node) const {
deba@57:       node.id = first_node;
deba@57:     }
deba@57: 
deba@57:     void next(Node& node) const {
deba@57:       node.id = nodes[node.id].next;
deba@57:     }
deba@57: 
deba@57: 
alpar@209:     void first(Arc& arc) const {
deba@57:       int n;
alpar@209:       for(n = first_node;
kpeter@739:           n != -1 && nodes[n].first_out == -1;
alpar@209:           n = nodes[n].next) {}
kpeter@739:       arc.id = (n == -1) ? -1 : nodes[n].first_out;
deba@57:     }
deba@57: 
deba@57:     void next(Arc& arc) const {
kpeter@739:       if (arcs[arc.id].next_out != -1) {
kpeter@739:         arc.id = arcs[arc.id].next_out;
deba@57:       } else {
alpar@209:         int n;
kpeter@739:         for(n = nodes[arcs[arc.id].source].next;
kpeter@739:             n != -1 && nodes[n].first_out == -1;
alpar@209:             n = nodes[n].next) {}
kpeter@739:         arc.id = (n == -1) ? -1 : nodes[n].first_out;
alpar@209:       }
deba@57:     }
deba@57: 
deba@57:     void firstOut(Arc &e, const Node& v) const {
deba@57:       e.id = nodes[v.id].first_out;
deba@57:     }
deba@57:     void nextOut(Arc &e) const {
deba@57:       e.id=arcs[e.id].next_out;
deba@57:     }
deba@57: 
deba@57:     void firstIn(Arc &e, const Node& v) const {
deba@57:       e.id = nodes[v.id].first_in;
deba@57:     }
deba@57:     void nextIn(Arc &e) const {
deba@57:       e.id=arcs[e.id].next_in;
deba@57:     }
deba@57: 
alpar@209: 
deba@57:     static int id(Node v) { return v.id; }
deba@57:     static int id(Arc e) { return e.id; }
deba@57: 
deba@57:     static Node nodeFromId(int id) { return Node(id);}
deba@57:     static Arc arcFromId(int id) { return Arc(id);}
deba@57: 
alpar@209:     bool valid(Node n) const {
alpar@209:       return n.id >= 0 && n.id < static_cast<int>(nodes.size()) &&
alpar@209:         nodes[n.id].prev != -2;
deba@149:     }
deba@149: 
alpar@209:     bool valid(Arc a) const {
alpar@209:       return a.id >= 0 && a.id < static_cast<int>(arcs.size()) &&
alpar@209:         arcs[a.id].prev_in != -2;
deba@149:     }
deba@149: 
alpar@209:     Node addNode() {
deba@57:       int n;
alpar@209: 
deba@57:       if(first_free_node==-1) {
alpar@209:         n = nodes.size();
alpar@209:         nodes.push_back(NodeT());
deba@57:       } else {
alpar@209:         n = first_free_node;
alpar@209:         first_free_node = nodes[n].next;
deba@57:       }
alpar@209: 
deba@57:       nodes[n].next = first_node;
deba@57:       if(first_node != -1) nodes[first_node].prev = n;
deba@57:       first_node = n;
deba@57:       nodes[n].prev = -1;
alpar@209: 
deba@57:       nodes[n].first_in = nodes[n].first_out = -1;
alpar@209: 
deba@57:       return Node(n);
deba@57:     }
alpar@209: 
deba@57:     Arc addArc(Node u, Node v) {
alpar@209:       int n;
deba@57: 
deba@57:       if (first_free_arc == -1) {
alpar@209:         n = arcs.size();
alpar@209:         arcs.push_back(ArcT());
deba@57:       } else {
alpar@209:         n = first_free_arc;
alpar@209:         first_free_arc = arcs[n].next_in;
deba@57:       }
alpar@209: 
alpar@209:       arcs[n].source = u.id;
deba@57:       arcs[n].target = v.id;
deba@57: 
deba@57:       arcs[n].next_out = nodes[u.id].first_out;
deba@57:       if(nodes[u.id].first_out != -1) {
alpar@209:         arcs[nodes[u.id].first_out].prev_out = n;
deba@57:       }
alpar@209: 
deba@57:       arcs[n].next_in = nodes[v.id].first_in;
deba@57:       if(nodes[v.id].first_in != -1) {
alpar@209:         arcs[nodes[v.id].first_in].prev_in = n;
deba@57:       }
alpar@209: 
deba@57:       arcs[n].prev_in = arcs[n].prev_out = -1;
alpar@209: 
deba@57:       nodes[u.id].first_out = nodes[v.id].first_in = n;
deba@57: 
deba@57:       return Arc(n);
deba@57:     }
alpar@209: 
deba@57:     void erase(const Node& node) {
deba@57:       int n = node.id;
alpar@209: 
deba@57:       if(nodes[n].next != -1) {
alpar@209:         nodes[nodes[n].next].prev = nodes[n].prev;
deba@57:       }
alpar@209: 
deba@57:       if(nodes[n].prev != -1) {
alpar@209:         nodes[nodes[n].prev].next = nodes[n].next;
deba@57:       } else {
alpar@209:         first_node = nodes[n].next;
deba@57:       }
alpar@209: 
deba@57:       nodes[n].next = first_free_node;
deba@57:       first_free_node = n;
deba@149:       nodes[n].prev = -2;
deba@57: 
deba@57:     }
alpar@209: 
deba@57:     void erase(const Arc& arc) {
deba@57:       int n = arc.id;
alpar@209: 
deba@57:       if(arcs[n].next_in!=-1) {
alpar@209:         arcs[arcs[n].next_in].prev_in = arcs[n].prev_in;
deba@57:       }
deba@57: 
deba@57:       if(arcs[n].prev_in!=-1) {
alpar@209:         arcs[arcs[n].prev_in].next_in = arcs[n].next_in;
deba@57:       } else {
alpar@209:         nodes[arcs[n].target].first_in = arcs[n].next_in;
deba@57:       }
deba@57: 
alpar@209: 
deba@57:       if(arcs[n].next_out!=-1) {
alpar@209:         arcs[arcs[n].next_out].prev_out = arcs[n].prev_out;
alpar@209:       }
deba@57: 
deba@57:       if(arcs[n].prev_out!=-1) {
alpar@209:         arcs[arcs[n].prev_out].next_out = arcs[n].next_out;
deba@57:       } else {
alpar@209:         nodes[arcs[n].source].first_out = arcs[n].next_out;
deba@57:       }
alpar@209: 
deba@57:       arcs[n].next_in = first_free_arc;
deba@149:       first_free_arc = n;
deba@149:       arcs[n].prev_in = -2;
deba@57:     }
deba@57: 
deba@57:     void clear() {
deba@57:       arcs.clear();
deba@57:       nodes.clear();
deba@57:       first_node = first_free_node = first_free_arc = -1;
deba@57:     }
deba@57: 
deba@57:   protected:
alpar@209:     void changeTarget(Arc e, Node n)
deba@57:     {
deba@57:       if(arcs[e.id].next_in != -1)
alpar@209:         arcs[arcs[e.id].next_in].prev_in = arcs[e.id].prev_in;
deba@57:       if(arcs[e.id].prev_in != -1)
alpar@209:         arcs[arcs[e.id].prev_in].next_in = arcs[e.id].next_in;
deba@57:       else nodes[arcs[e.id].target].first_in = arcs[e.id].next_in;
deba@57:       if (nodes[n.id].first_in != -1) {
alpar@209:         arcs[nodes[n.id].first_in].prev_in = e.id;
deba@57:       }
deba@57:       arcs[e.id].target = n.id;
deba@57:       arcs[e.id].prev_in = -1;
deba@57:       arcs[e.id].next_in = nodes[n.id].first_in;
deba@57:       nodes[n.id].first_in = e.id;
deba@57:     }
alpar@209:     void changeSource(Arc e, Node n)
deba@57:     {
deba@57:       if(arcs[e.id].next_out != -1)
alpar@209:         arcs[arcs[e.id].next_out].prev_out = arcs[e.id].prev_out;
deba@57:       if(arcs[e.id].prev_out != -1)
alpar@209:         arcs[arcs[e.id].prev_out].next_out = arcs[e.id].next_out;
deba@57:       else nodes[arcs[e.id].source].first_out = arcs[e.id].next_out;
deba@57:       if (nodes[n.id].first_out != -1) {
alpar@209:         arcs[nodes[n.id].first_out].prev_out = e.id;
deba@57:       }
deba@57:       arcs[e.id].source = n.id;
deba@57:       arcs[e.id].prev_out = -1;
deba@57:       arcs[e.id].next_out = nodes[n.id].first_out;
deba@57:       nodes[n.id].first_out = e.id;
deba@57:     }
deba@57: 
deba@57:   };
deba@57: 
deba@57:   typedef DigraphExtender<ListDigraphBase> ExtendedListDigraphBase;
deba@57: 
kpeter@73:   /// \addtogroup graphs
deba@57:   /// @{
deba@57: 
alpar@209:   ///A general directed graph structure.
deba@57: 
kpeter@735:   ///\ref ListDigraph is a versatile and fast directed graph
kpeter@735:   ///implementation based on linked lists that are stored in
alpar@209:   ///\c std::vector structures.
deba@57:   ///
kpeter@735:   ///This type fully conforms to the \ref concepts::Digraph "Digraph concept"
kpeter@735:   ///and it also provides several useful additional functionalities.
kpeter@735:   ///Most of its member functions and nested classes are documented
kpeter@73:   ///only in the concept class.
deba@57:   ///
kpeter@787:   ///This class provides only linear time counting for nodes and arcs.
kpeter@787:   ///
kpeter@73:   ///\sa concepts::Digraph
kpeter@735:   ///\sa ListGraph
deba@57:   class ListDigraph : public ExtendedListDigraphBase {
kpeter@617:     typedef ExtendedListDigraphBase Parent;
kpeter@617: 
deba@57:   private:
kpeter@735:     /// Digraphs are \e not copy constructible. Use DigraphCopy instead.
deba@57:     ListDigraph(const ListDigraph &) :ExtendedListDigraphBase() {};
kpeter@735:     /// \brief Assignment of a digraph to another one is \e not allowed.
kpeter@735:     /// Use DigraphCopy instead.
deba@57:     void operator=(const ListDigraph &) {}
deba@57:   public:
deba@57: 
deba@57:     /// Constructor
alpar@209: 
deba@57:     /// Constructor.
deba@57:     ///
deba@57:     ListDigraph() {}
deba@57: 
deba@57:     ///Add a new node to the digraph.
alpar@209: 
kpeter@735:     ///This function adds a new node to the digraph.
kpeter@559:     ///\return The new node.
deba@57:     Node addNode() { return Parent::addNode(); }
deba@57: 
deba@57:     ///Add a new arc to the digraph.
alpar@209: 
kpeter@735:     ///This function adds a new arc to the digraph with source node \c s
deba@57:     ///and target node \c t.
kpeter@559:     ///\return The new arc.
kpeter@735:     Arc addArc(Node s, Node t) {
alpar@209:       return Parent::addArc(s, t);
deba@57:     }
deba@57: 
deba@234:     ///\brief Erase a node from the digraph.
deba@234:     ///
kpeter@787:     ///This function erases the given node along with its outgoing and
kpeter@787:     ///incoming arcs from the digraph.
kpeter@787:     ///
kpeter@787:     ///\note All iterators referencing the removed node or the connected
kpeter@787:     ///arcs are invalidated, of course.
kpeter@735:     void erase(Node n) { Parent::erase(n); }
deba@234: 
deba@234:     ///\brief Erase an arc from the digraph.
deba@234:     ///
kpeter@735:     ///This function erases the given arc from the digraph.
kpeter@787:     ///
kpeter@787:     ///\note All iterators referencing the removed arc are invalidated,
kpeter@787:     ///of course.
kpeter@735:     void erase(Arc a) { Parent::erase(a); }
deba@234: 
deba@149:     /// Node validity check
deba@149: 
kpeter@735:     /// This function gives back \c true if the given node is valid,
kpeter@735:     /// i.e. it is a real node of the digraph.
deba@149:     ///
kpeter@735:     /// \warning A removed node could become valid again if new nodes are
kpeter@735:     /// added to the digraph.
deba@149:     bool valid(Node n) const { return Parent::valid(n); }
deba@149: 
deba@149:     /// Arc validity check
deba@149: 
kpeter@735:     /// This function gives back \c true if the given arc is valid,
kpeter@735:     /// i.e. it is a real arc of the digraph.
deba@149:     ///
kpeter@735:     /// \warning A removed arc could become valid again if new arcs are
kpeter@735:     /// added to the digraph.
deba@149:     bool valid(Arc a) const { return Parent::valid(a); }
deba@149: 
kpeter@735:     /// Change the target node of an arc
deba@57: 
kpeter@735:     /// This function changes the target node of the given arc \c a to \c n.
deba@57:     ///
kpeter@735:     ///\note \c ArcIt and \c OutArcIt iterators referencing the changed
kpeter@786:     ///arc remain valid, but \c InArcIt iterators are invalidated.
kpeter@73:     ///
deba@57:     ///\warning This functionality cannot be used together with the Snapshot
deba@57:     ///feature.
deba@235:     void changeTarget(Arc a, Node n) {
deba@235:       Parent::changeTarget(a,n);
deba@57:     }
kpeter@735:     /// Change the source node of an arc
deba@57: 
kpeter@735:     /// This function changes the source node of the given arc \c a to \c n.
deba@57:     ///
kpeter@735:     ///\note \c InArcIt iterators referencing the changed arc remain
kpeter@786:     ///valid, but \c ArcIt and \c OutArcIt iterators are invalidated.
kpeter@73:     ///
deba@57:     ///\warning This functionality cannot be used together with the Snapshot
deba@57:     ///feature.
deba@235:     void changeSource(Arc a, Node n) {
deba@235:       Parent::changeSource(a,n);
deba@57:     }
deba@57: 
kpeter@735:     /// Reverse the direction of an arc.
deba@57: 
kpeter@735:     /// This function reverses the direction of the given arc.
kpeter@735:     ///\note \c ArcIt, \c OutArcIt and \c InArcIt iterators referencing
kpeter@735:     ///the changed arc are invalidated.
kpeter@73:     ///
deba@57:     ///\warning This functionality cannot be used together with the Snapshot
deba@57:     ///feature.
kpeter@735:     void reverseArc(Arc a) {
kpeter@735:       Node t=target(a);
kpeter@735:       changeTarget(a,source(a));
kpeter@735:       changeSource(a,t);
deba@57:     }
deba@57: 
deba@57:     ///Contract two nodes.
deba@57: 
kpeter@735:     ///This function contracts the given two nodes.
kpeter@735:     ///Node \c v is removed, but instead of deleting its
kpeter@735:     ///incident arcs, they are joined to node \c u.
kpeter@735:     ///If the last parameter \c r is \c true (this is the default value),
kpeter@735:     ///then the newly created loops are removed.
deba@57:     ///
kpeter@735:     ///\note The moved arcs are joined to node \c u using changeSource()
kpeter@735:     ///or changeTarget(), thus \c ArcIt and \c OutArcIt iterators are
kpeter@735:     ///invalidated for the outgoing arcs of node \c v and \c InArcIt
kpeter@735:     ///iterators are invalidated for the incomming arcs of \c v.
kpeter@735:     ///Moreover all iterators referencing node \c v or the removed 
kpeter@735:     ///loops are also invalidated. Other iterators remain valid.
kpeter@73:     ///
deba@57:     ///\warning This functionality cannot be used together with the Snapshot
deba@57:     ///feature.
kpeter@735:     void contract(Node u, Node v, bool r = true)
deba@57:     {
kpeter@735:       for(OutArcIt e(*this,v);e!=INVALID;) {
alpar@209:         OutArcIt f=e;
alpar@209:         ++f;
kpeter@735:         if(r && target(e)==u) erase(e);
kpeter@735:         else changeSource(e,u);
alpar@209:         e=f;
deba@57:       }
kpeter@735:       for(InArcIt e(*this,v);e!=INVALID;) {
alpar@209:         InArcIt f=e;
alpar@209:         ++f;
kpeter@735:         if(r && source(e)==u) erase(e);
kpeter@735:         else changeTarget(e,u);
alpar@209:         e=f;
deba@57:       }
kpeter@735:       erase(v);
deba@57:     }
deba@57: 
deba@57:     ///Split a node.
deba@57: 
kpeter@735:     ///This function splits the given node. First, a new node is added
kpeter@735:     ///to the digraph, then the source of each outgoing arc of node \c n
kpeter@735:     ///is moved to this new node.
kpeter@735:     ///If the second parameter \c connect is \c true (this is the default
kpeter@735:     ///value), then a new arc from node \c n to the newly created node
kpeter@735:     ///is also added.
deba@57:     ///\return The newly created node.
deba@57:     ///
kpeter@738:     ///\note All iterators remain valid.
deba@57:     ///
kpeter@735:     ///\warning This functionality cannot be used together with the
kpeter@73:     ///Snapshot feature.
deba@57:     Node split(Node n, bool connect = true) {
deba@57:       Node b = addNode();
kpeter@738:       nodes[b.id].first_out=nodes[n.id].first_out;
kpeter@738:       nodes[n.id].first_out=-1;
kpeter@738:       for(int i=nodes[b.id].first_out; i!=-1; i=arcs[i].next_out) {
kpeter@738:         arcs[i].source=b.id;
deba@57:       }
deba@57:       if (connect) addArc(n,b);
deba@57:       return b;
deba@57:     }
alpar@209: 
deba@57:     ///Split an arc.
deba@57: 
kpeter@735:     ///This function splits the given arc. First, a new node \c v is
kpeter@735:     ///added to the digraph, then the target node of the original arc
kpeter@735:     ///is set to \c v. Finally, an arc from \c v to the original target
kpeter@735:     ///is added.
kpeter@735:     ///\return The newly created node.
kpeter@73:     ///
kpeter@735:     ///\note \c InArcIt iterators referencing the original arc are
kpeter@735:     ///invalidated. Other iterators remain valid.
kpeter@73:     ///
kpeter@73:     ///\warning This functionality cannot be used together with the
kpeter@73:     ///Snapshot feature.
kpeter@735:     Node split(Arc a) {
kpeter@735:       Node v = addNode();
kpeter@735:       addArc(v,target(a));
kpeter@735:       changeTarget(a,v);
kpeter@735:       return v;
deba@57:     }
alpar@209: 
kpeter@735:     ///Clear the digraph.
kpeter@735: 
kpeter@735:     ///This function erases all nodes and arcs from the digraph.
kpeter@735:     ///
kpeter@787:     ///\note All iterators of the digraph are invalidated, of course.
kpeter@735:     void clear() {
kpeter@735:       Parent::clear();
kpeter@735:     }
kpeter@735: 
kpeter@735:     /// Reserve memory for nodes.
kpeter@735: 
kpeter@735:     /// Using this function, it is possible to avoid superfluous memory
kpeter@735:     /// allocation: if you know that the digraph you want to build will
kpeter@735:     /// be large (e.g. it will contain millions of nodes and/or arcs),
kpeter@735:     /// then it is worth reserving space for this amount before starting
kpeter@735:     /// to build the digraph.
kpeter@735:     /// \sa reserveArc()
kpeter@735:     void reserveNode(int n) { nodes.reserve(n); };
kpeter@735: 
kpeter@735:     /// Reserve memory for arcs.
kpeter@735: 
kpeter@735:     /// Using this function, it is possible to avoid superfluous memory
kpeter@735:     /// allocation: if you know that the digraph you want to build will
kpeter@735:     /// be large (e.g. it will contain millions of nodes and/or arcs),
kpeter@735:     /// then it is worth reserving space for this amount before starting
kpeter@735:     /// to build the digraph.
kpeter@735:     /// \sa reserveNode()
kpeter@735:     void reserveArc(int m) { arcs.reserve(m); };
kpeter@735: 
deba@57:     /// \brief Class to make a snapshot of the digraph and restore
kpeter@73:     /// it later.
deba@57:     ///
kpeter@73:     /// Class to make a snapshot of the digraph and restore it later.
deba@57:     ///
deba@57:     /// The newly added nodes and arcs can be removed using the
deba@57:     /// restore() function.
deba@57:     ///
kpeter@735:     /// \note After a state is restored, you cannot restore a later state, 
kpeter@735:     /// i.e. you cannot add the removed nodes and arcs again using
kpeter@735:     /// another Snapshot instance.
kpeter@735:     ///
kpeter@735:     /// \warning Node and arc deletions and other modifications (e.g.
kpeter@735:     /// reversing, contracting, splitting arcs or nodes) cannot be
alpar@209:     /// restored. These events invalidate the snapshot.
kpeter@786:     /// However, the arcs and nodes that were added to the digraph after
kpeter@735:     /// making the current snapshot can be removed without invalidating it.
deba@57:     class Snapshot {
deba@57:     protected:
deba@57: 
deba@57:       typedef Parent::NodeNotifier NodeNotifier;
deba@57: 
deba@57:       class NodeObserverProxy : public NodeNotifier::ObserverBase {
deba@57:       public:
deba@57: 
deba@57:         NodeObserverProxy(Snapshot& _snapshot)
deba@57:           : snapshot(_snapshot) {}
deba@57: 
deba@57:         using NodeNotifier::ObserverBase::attach;
deba@57:         using NodeNotifier::ObserverBase::detach;
deba@57:         using NodeNotifier::ObserverBase::attached;
alpar@209: 
deba@57:       protected:
alpar@209: 
deba@57:         virtual void add(const Node& node) {
deba@57:           snapshot.addNode(node);
deba@57:         }
deba@57:         virtual void add(const std::vector<Node>& nodes) {
deba@57:           for (int i = nodes.size() - 1; i >= 0; ++i) {
deba@57:             snapshot.addNode(nodes[i]);
deba@57:           }
deba@57:         }
deba@57:         virtual void erase(const Node& node) {
deba@57:           snapshot.eraseNode(node);
deba@57:         }
deba@57:         virtual void erase(const std::vector<Node>& nodes) {
deba@57:           for (int i = 0; i < int(nodes.size()); ++i) {
deba@57:             snapshot.eraseNode(nodes[i]);
deba@57:           }
deba@57:         }
deba@57:         virtual void build() {
deba@57:           Node node;
deba@57:           std::vector<Node> nodes;
alpar@209:           for (notifier()->first(node); node != INVALID;
deba@57:                notifier()->next(node)) {
deba@57:             nodes.push_back(node);
deba@57:           }
deba@57:           for (int i = nodes.size() - 1; i >= 0; --i) {
deba@57:             snapshot.addNode(nodes[i]);
deba@57:           }
deba@57:         }
deba@57:         virtual void clear() {
deba@57:           Node node;
alpar@209:           for (notifier()->first(node); node != INVALID;
deba@57:                notifier()->next(node)) {
deba@57:             snapshot.eraseNode(node);
deba@57:           }
deba@57:         }
deba@57: 
deba@57:         Snapshot& snapshot;
deba@57:       };
deba@57: 
deba@57:       class ArcObserverProxy : public ArcNotifier::ObserverBase {
deba@57:       public:
deba@57: 
deba@57:         ArcObserverProxy(Snapshot& _snapshot)
deba@57:           : snapshot(_snapshot) {}
deba@57: 
deba@57:         using ArcNotifier::ObserverBase::attach;
deba@57:         using ArcNotifier::ObserverBase::detach;
deba@57:         using ArcNotifier::ObserverBase::attached;
alpar@209: 
deba@57:       protected:
deba@57: 
deba@57:         virtual void add(const Arc& arc) {
deba@57:           snapshot.addArc(arc);
deba@57:         }
deba@57:         virtual void add(const std::vector<Arc>& arcs) {
deba@57:           for (int i = arcs.size() - 1; i >= 0; ++i) {
deba@57:             snapshot.addArc(arcs[i]);
deba@57:           }
deba@57:         }
deba@57:         virtual void erase(const Arc& arc) {
deba@57:           snapshot.eraseArc(arc);
deba@57:         }
deba@57:         virtual void erase(const std::vector<Arc>& arcs) {
deba@57:           for (int i = 0; i < int(arcs.size()); ++i) {
deba@57:             snapshot.eraseArc(arcs[i]);
deba@57:           }
deba@57:         }
deba@57:         virtual void build() {
deba@57:           Arc arc;
deba@57:           std::vector<Arc> arcs;
alpar@209:           for (notifier()->first(arc); arc != INVALID;
deba@57:                notifier()->next(arc)) {
deba@57:             arcs.push_back(arc);
deba@57:           }
deba@57:           for (int i = arcs.size() - 1; i >= 0; --i) {
deba@57:             snapshot.addArc(arcs[i]);
deba@57:           }
deba@57:         }
deba@57:         virtual void clear() {
deba@57:           Arc arc;
alpar@209:           for (notifier()->first(arc); arc != INVALID;
deba@57:                notifier()->next(arc)) {
deba@57:             snapshot.eraseArc(arc);
deba@57:           }
deba@57:         }
deba@57: 
deba@57:         Snapshot& snapshot;
deba@57:       };
alpar@209: 
deba@57:       ListDigraph *digraph;
deba@57: 
deba@57:       NodeObserverProxy node_observer_proxy;
deba@57:       ArcObserverProxy arc_observer_proxy;
deba@57: 
deba@57:       std::list<Node> added_nodes;
deba@57:       std::list<Arc> added_arcs;
deba@57: 
deba@57: 
deba@57:       void addNode(const Node& node) {
alpar@209:         added_nodes.push_front(node);
deba@57:       }
deba@57:       void eraseNode(const Node& node) {
alpar@209:         std::list<Node>::iterator it =
deba@57:           std::find(added_nodes.begin(), added_nodes.end(), node);
deba@57:         if (it == added_nodes.end()) {
deba@57:           clear();
deba@57:           arc_observer_proxy.detach();
deba@57:           throw NodeNotifier::ImmediateDetach();
deba@57:         } else {
deba@57:           added_nodes.erase(it);
deba@57:         }
deba@57:       }
deba@57: 
deba@57:       void addArc(const Arc& arc) {
alpar@209:         added_arcs.push_front(arc);
deba@57:       }
deba@57:       void eraseArc(const Arc& arc) {
alpar@209:         std::list<Arc>::iterator it =
deba@57:           std::find(added_arcs.begin(), added_arcs.end(), arc);
deba@57:         if (it == added_arcs.end()) {
deba@57:           clear();
alpar@209:           node_observer_proxy.detach();
deba@57:           throw ArcNotifier::ImmediateDetach();
deba@57:         } else {
deba@57:           added_arcs.erase(it);
alpar@209:         }
deba@57:       }
deba@57: 
deba@57:       void attach(ListDigraph &_digraph) {
alpar@209:         digraph = &_digraph;
alpar@209:         node_observer_proxy.attach(digraph->notifier(Node()));
deba@57:         arc_observer_proxy.attach(digraph->notifier(Arc()));
deba@57:       }
alpar@209: 
deba@57:       void detach() {
alpar@209:         node_observer_proxy.detach();
alpar@209:         arc_observer_proxy.detach();
deba@57:       }
deba@57: 
deba@57:       bool attached() const {
deba@57:         return node_observer_proxy.attached();
deba@57:       }
deba@57: 
deba@57:       void clear() {
deba@57:         added_nodes.clear();
alpar@209:         added_arcs.clear();
deba@57:       }
deba@57: 
deba@57:     public:
deba@57: 
deba@57:       /// \brief Default constructor.
deba@57:       ///
deba@57:       /// Default constructor.
kpeter@735:       /// You have to call save() to actually make a snapshot.
alpar@209:       Snapshot()
alpar@209:         : digraph(0), node_observer_proxy(*this),
deba@57:           arc_observer_proxy(*this) {}
alpar@209: 
deba@57:       /// \brief Constructor that immediately makes a snapshot.
alpar@209:       ///
kpeter@735:       /// This constructor immediately makes a snapshot of the given digraph.
kpeter@735:       Snapshot(ListDigraph &gr)
alpar@209:         : node_observer_proxy(*this),
deba@57:           arc_observer_proxy(*this) {
kpeter@735:         attach(gr);
deba@57:       }
alpar@209: 
deba@57:       /// \brief Make a snapshot.
deba@57:       ///
kpeter@735:       /// This function makes a snapshot of the given digraph.
kpeter@735:       /// It can be called more than once. In case of a repeated
deba@57:       /// call, the previous snapshot gets lost.
kpeter@735:       void save(ListDigraph &gr) {
deba@57:         if (attached()) {
deba@57:           detach();
deba@57:           clear();
deba@57:         }
kpeter@735:         attach(gr);
deba@57:       }
alpar@209: 
deba@57:       /// \brief Undo the changes until the last snapshot.
kpeter@735:       ///
kpeter@735:       /// This function undos the changes until the last snapshot
kpeter@735:       /// created by save() or Snapshot(ListDigraph&).
kpeter@740:       ///
kpeter@740:       /// \warning This method invalidates the snapshot, i.e. repeated
kpeter@740:       /// restoring is not supported unless you call save() again.
deba@57:       void restore() {
alpar@209:         detach();
alpar@209:         for(std::list<Arc>::iterator it = added_arcs.begin();
deba@57:             it != added_arcs.end(); ++it) {
alpar@209:           digraph->erase(*it);
alpar@209:         }
alpar@209:         for(std::list<Node>::iterator it = added_nodes.begin();
deba@57:             it != added_nodes.end(); ++it) {
alpar@209:           digraph->erase(*it);
alpar@209:         }
deba@57:         clear();
deba@57:       }
deba@57: 
kpeter@735:       /// \brief Returns \c true if the snapshot is valid.
deba@57:       ///
kpeter@735:       /// This function returns \c true if the snapshot is valid.
deba@57:       bool valid() const {
deba@57:         return attached();
deba@57:       }
deba@57:     };
alpar@209: 
deba@57:   };
deba@57: 
deba@57:   ///@}
deba@57: 
deba@57:   class ListGraphBase {
deba@57: 
deba@57:   protected:
deba@57: 
deba@57:     struct NodeT {
deba@57:       int first_out;
deba@57:       int prev, next;
deba@57:     };
alpar@209: 
deba@57:     struct ArcT {
deba@57:       int target;
deba@57:       int prev_out, next_out;
deba@57:     };
deba@57: 
deba@57:     std::vector<NodeT> nodes;
deba@57: 
deba@57:     int first_node;
deba@57: 
deba@57:     int first_free_node;
deba@57: 
deba@57:     std::vector<ArcT> arcs;
deba@57: 
deba@57:     int first_free_arc;
alpar@209: 
deba@57:   public:
alpar@209: 
kpeter@617:     typedef ListGraphBase Graph;
deba@57: 
deba@57:     class Node {
deba@57:       friend class ListGraphBase;
deba@57:     protected:
deba@57: 
deba@57:       int id;
deba@57:       explicit Node(int pid) { id = pid;}
deba@57: 
deba@57:     public:
deba@57:       Node() {}
deba@57:       Node (Invalid) { id = -1; }
deba@57:       bool operator==(const Node& node) const {return id == node.id;}
deba@57:       bool operator!=(const Node& node) const {return id != node.id;}
deba@57:       bool operator<(const Node& node) const {return id < node.id;}
deba@57:     };
deba@57: 
deba@57:     class Edge {
deba@57:       friend class ListGraphBase;
deba@57:     protected:
deba@57: 
deba@57:       int id;
deba@57:       explicit Edge(int pid) { id = pid;}
deba@57: 
deba@57:     public:
deba@57:       Edge() {}
deba@57:       Edge (Invalid) { id = -1; }
kpeter@73:       bool operator==(const Edge& edge) const {return id == edge.id;}
kpeter@73:       bool operator!=(const Edge& edge) const {return id != edge.id;}
kpeter@73:       bool operator<(const Edge& edge) const {return id < edge.id;}
deba@57:     };
deba@57: 
deba@57:     class Arc {
deba@57:       friend class ListGraphBase;
deba@57:     protected:
deba@57: 
deba@57:       int id;
deba@57:       explicit Arc(int pid) { id = pid;}
deba@57: 
deba@57:     public:
kpeter@329:       operator Edge() const {
kpeter@329:         return id != -1 ? edgeFromId(id / 2) : INVALID;
deba@238:       }
deba@57: 
deba@57:       Arc() {}
deba@57:       Arc (Invalid) { id = -1; }
deba@57:       bool operator==(const Arc& arc) const {return id == arc.id;}
deba@57:       bool operator!=(const Arc& arc) const {return id != arc.id;}
deba@57:       bool operator<(const Arc& arc) const {return id < arc.id;}
deba@57:     };
deba@57: 
deba@57:     ListGraphBase()
deba@57:       : nodes(), first_node(-1),
alpar@209:         first_free_node(-1), arcs(), first_free_arc(-1) {}
deba@57: 
alpar@209: 
alpar@209:     int maxNodeId() const { return nodes.size()-1; }
deba@57:     int maxEdgeId() const { return arcs.size() / 2 - 1; }
deba@57:     int maxArcId() const { return arcs.size()-1; }
deba@57: 
deba@57:     Node source(Arc e) const { return Node(arcs[e.id ^ 1].target); }
deba@57:     Node target(Arc e) const { return Node(arcs[e.id].target); }
deba@57: 
deba@57:     Node u(Edge e) const { return Node(arcs[2 * e.id].target); }
deba@57:     Node v(Edge e) const { return Node(arcs[2 * e.id + 1].target); }
deba@57: 
deba@57:     static bool direction(Arc e) {
deba@57:       return (e.id & 1) == 1;
deba@57:     }
deba@57: 
deba@57:     static Arc direct(Edge e, bool d) {
deba@57:       return Arc(e.id * 2 + (d ? 1 : 0));
deba@57:     }
deba@57: 
alpar@209:     void first(Node& node) const {
deba@57:       node.id = first_node;
deba@57:     }
deba@57: 
deba@57:     void next(Node& node) const {
deba@57:       node.id = nodes[node.id].next;
deba@57:     }
deba@57: 
alpar@209:     void first(Arc& e) const {
deba@57:       int n = first_node;
deba@57:       while (n != -1 && nodes[n].first_out == -1) {
deba@57:         n = nodes[n].next;
deba@57:       }
deba@57:       e.id = (n == -1) ? -1 : nodes[n].first_out;
deba@57:     }
deba@57: 
deba@57:     void next(Arc& e) const {
deba@57:       if (arcs[e.id].next_out != -1) {
alpar@209:         e.id = arcs[e.id].next_out;
deba@57:       } else {
alpar@209:         int n = nodes[arcs[e.id ^ 1].target].next;
deba@57:         while(n != -1 && nodes[n].first_out == -1) {
deba@57:           n = nodes[n].next;
deba@57:         }
alpar@209:         e.id = (n == -1) ? -1 : nodes[n].first_out;
alpar@209:       }
deba@57:     }
deba@57: 
alpar@209:     void first(Edge& e) const {
deba@57:       int n = first_node;
deba@57:       while (n != -1) {
deba@57:         e.id = nodes[n].first_out;
deba@57:         while ((e.id & 1) != 1) {
deba@57:           e.id = arcs[e.id].next_out;
deba@57:         }
deba@57:         if (e.id != -1) {
deba@57:           e.id /= 2;
deba@57:           return;
alpar@209:         }
deba@57:         n = nodes[n].next;
deba@57:       }
deba@57:       e.id = -1;
deba@57:     }
deba@57: 
deba@57:     void next(Edge& e) const {
deba@57:       int n = arcs[e.id * 2].target;
deba@57:       e.id = arcs[(e.id * 2) | 1].next_out;
deba@57:       while ((e.id & 1) != 1) {
deba@57:         e.id = arcs[e.id].next_out;
deba@57:       }
deba@57:       if (e.id != -1) {
deba@57:         e.id /= 2;
deba@57:         return;
alpar@209:       }
deba@57:       n = nodes[n].next;
deba@57:       while (n != -1) {
deba@57:         e.id = nodes[n].first_out;
deba@57:         while ((e.id & 1) != 1) {
deba@57:           e.id = arcs[e.id].next_out;
deba@57:         }
deba@57:         if (e.id != -1) {
deba@57:           e.id /= 2;
deba@57:           return;
alpar@209:         }
deba@57:         n = nodes[n].next;
deba@57:       }
deba@57:       e.id = -1;
deba@57:     }
deba@57: 
deba@57:     void firstOut(Arc &e, const Node& v) const {
deba@57:       e.id = nodes[v.id].first_out;
deba@57:     }
deba@57:     void nextOut(Arc &e) const {
deba@57:       e.id = arcs[e.id].next_out;
deba@57:     }
deba@57: 
deba@57:     void firstIn(Arc &e, const Node& v) const {
deba@57:       e.id = ((nodes[v.id].first_out) ^ 1);
deba@57:       if (e.id == -2) e.id = -1;
deba@57:     }
deba@57:     void nextIn(Arc &e) const {
deba@57:       e.id = ((arcs[e.id ^ 1].next_out) ^ 1);
deba@57:       if (e.id == -2) e.id = -1;
deba@57:     }
deba@57: 
deba@57:     void firstInc(Edge &e, bool& d, const Node& v) const {
kpeter@73:       int a = nodes[v.id].first_out;
kpeter@73:       if (a != -1 ) {
kpeter@73:         e.id = a / 2;
kpeter@73:         d = ((a & 1) == 1);
deba@57:       } else {
deba@57:         e.id = -1;
deba@57:         d = true;
deba@57:       }
deba@57:     }
deba@57:     void nextInc(Edge &e, bool& d) const {
kpeter@73:       int a = (arcs[(e.id * 2) | (d ? 1 : 0)].next_out);
kpeter@73:       if (a != -1 ) {
kpeter@73:         e.id = a / 2;
kpeter@73:         d = ((a & 1) == 1);
deba@57:       } else {
deba@57:         e.id = -1;
deba@57:         d = true;
deba@57:       }
deba@57:     }
alpar@209: 
deba@57:     static int id(Node v) { return v.id; }
deba@57:     static int id(Arc e) { return e.id; }
deba@57:     static int id(Edge e) { return e.id; }
deba@57: 
deba@57:     static Node nodeFromId(int id) { return Node(id);}
deba@57:     static Arc arcFromId(int id) { return Arc(id);}
deba@57:     static Edge edgeFromId(int id) { return Edge(id);}
deba@57: 
alpar@209:     bool valid(Node n) const {
alpar@209:       return n.id >= 0 && n.id < static_cast<int>(nodes.size()) &&
alpar@209:         nodes[n.id].prev != -2;
deba@149:     }
deba@149: 
alpar@209:     bool valid(Arc a) const {
alpar@209:       return a.id >= 0 && a.id < static_cast<int>(arcs.size()) &&
alpar@209:         arcs[a.id].prev_out != -2;
deba@149:     }
deba@149: 
alpar@209:     bool valid(Edge e) const {
alpar@209:       return e.id >= 0 && 2 * e.id < static_cast<int>(arcs.size()) &&
alpar@209:         arcs[2 * e.id].prev_out != -2;
deba@149:     }
deba@149: 
alpar@209:     Node addNode() {
deba@57:       int n;
alpar@209: 
deba@57:       if(first_free_node==-1) {
alpar@209:         n = nodes.size();
alpar@209:         nodes.push_back(NodeT());
deba@57:       } else {
alpar@209:         n = first_free_node;
alpar@209:         first_free_node = nodes[n].next;
deba@57:       }
alpar@209: 
deba@57:       nodes[n].next = first_node;
deba@57:       if (first_node != -1) nodes[first_node].prev = n;
deba@57:       first_node = n;
deba@57:       nodes[n].prev = -1;
alpar@209: 
deba@57:       nodes[n].first_out = -1;
alpar@209: 
deba@57:       return Node(n);
deba@57:     }
alpar@209: 
deba@57:     Edge addEdge(Node u, Node v) {
alpar@209:       int n;
deba@57: 
deba@57:       if (first_free_arc == -1) {
alpar@209:         n = arcs.size();
alpar@209:         arcs.push_back(ArcT());
alpar@209:         arcs.push_back(ArcT());
deba@57:       } else {
alpar@209:         n = first_free_arc;
alpar@209:         first_free_arc = arcs[n].next_out;
deba@57:       }
alpar@209: 
deba@57:       arcs[n].target = u.id;
deba@57:       arcs[n | 1].target = v.id;
deba@57: 
deba@57:       arcs[n].next_out = nodes[v.id].first_out;
deba@57:       if (nodes[v.id].first_out != -1) {
alpar@209:         arcs[nodes[v.id].first_out].prev_out = n;
alpar@209:       }
deba@57:       arcs[n].prev_out = -1;
deba@57:       nodes[v.id].first_out = n;
alpar@209: 
deba@57:       arcs[n | 1].next_out = nodes[u.id].first_out;
deba@57:       if (nodes[u.id].first_out != -1) {
alpar@209:         arcs[nodes[u.id].first_out].prev_out = (n | 1);
deba@57:       }
alpar@209:       arcs[n | 1].prev_out = -1;
deba@57:       nodes[u.id].first_out = (n | 1);
deba@57: 
deba@57:       return Edge(n / 2);
deba@57:     }
alpar@209: 
deba@57:     void erase(const Node& node) {
deba@57:       int n = node.id;
alpar@209: 
deba@57:       if(nodes[n].next != -1) {
alpar@209:         nodes[nodes[n].next].prev = nodes[n].prev;
deba@57:       }
alpar@209: 
deba@57:       if(nodes[n].prev != -1) {
alpar@209:         nodes[nodes[n].prev].next = nodes[n].next;
deba@57:       } else {
alpar@209:         first_node = nodes[n].next;
deba@57:       }
alpar@209: 
deba@57:       nodes[n].next = first_free_node;
deba@57:       first_free_node = n;
deba@149:       nodes[n].prev = -2;
deba@57:     }
alpar@209: 
kpeter@73:     void erase(const Edge& edge) {
kpeter@73:       int n = edge.id * 2;
alpar@209: 
deba@57:       if (arcs[n].next_out != -1) {
alpar@209:         arcs[arcs[n].next_out].prev_out = arcs[n].prev_out;
alpar@209:       }
deba@57: 
deba@57:       if (arcs[n].prev_out != -1) {
alpar@209:         arcs[arcs[n].prev_out].next_out = arcs[n].next_out;
deba@57:       } else {
alpar@209:         nodes[arcs[n | 1].target].first_out = arcs[n].next_out;
deba@57:       }
deba@57: 
deba@57:       if (arcs[n | 1].next_out != -1) {
alpar@209:         arcs[arcs[n | 1].next_out].prev_out = arcs[n | 1].prev_out;
alpar@209:       }
deba@57: 
deba@57:       if (arcs[n | 1].prev_out != -1) {
alpar@209:         arcs[arcs[n | 1].prev_out].next_out = arcs[n | 1].next_out;
deba@57:       } else {
alpar@209:         nodes[arcs[n].target].first_out = arcs[n | 1].next_out;
deba@57:       }
alpar@209: 
deba@57:       arcs[n].next_out = first_free_arc;
alpar@209:       first_free_arc = n;
deba@149:       arcs[n].prev_out = -2;
deba@149:       arcs[n | 1].prev_out = -2;
deba@57: 
deba@57:     }
deba@57: 
deba@57:     void clear() {
deba@57:       arcs.clear();
deba@57:       nodes.clear();
deba@57:       first_node = first_free_node = first_free_arc = -1;
deba@57:     }
deba@57: 
deba@57:   protected:
deba@57: 
deba@235:     void changeV(Edge e, Node n) {
deba@57:       if(arcs[2 * e.id].next_out != -1) {
alpar@209:         arcs[arcs[2 * e.id].next_out].prev_out = arcs[2 * e.id].prev_out;
deba@57:       }
deba@57:       if(arcs[2 * e.id].prev_out != -1) {
alpar@209:         arcs[arcs[2 * e.id].prev_out].next_out =
deba@57:           arcs[2 * e.id].next_out;
deba@57:       } else {
alpar@209:         nodes[arcs[(2 * e.id) | 1].target].first_out =
deba@57:           arcs[2 * e.id].next_out;
deba@57:       }
deba@57: 
deba@57:       if (nodes[n.id].first_out != -1) {
alpar@209:         arcs[nodes[n.id].first_out].prev_out = 2 * e.id;
deba@57:       }
deba@57:       arcs[(2 * e.id) | 1].target = n.id;
deba@57:       arcs[2 * e.id].prev_out = -1;
deba@57:       arcs[2 * e.id].next_out = nodes[n.id].first_out;
deba@57:       nodes[n.id].first_out = 2 * e.id;
deba@57:     }
deba@57: 
deba@235:     void changeU(Edge e, Node n) {
deba@57:       if(arcs[(2 * e.id) | 1].next_out != -1) {
alpar@209:         arcs[arcs[(2 * e.id) | 1].next_out].prev_out =
deba@57:           arcs[(2 * e.id) | 1].prev_out;
deba@57:       }
deba@57:       if(arcs[(2 * e.id) | 1].prev_out != -1) {
alpar@209:         arcs[arcs[(2 * e.id) | 1].prev_out].next_out =
deba@57:           arcs[(2 * e.id) | 1].next_out;
deba@57:       } else {
alpar@209:         nodes[arcs[2 * e.id].target].first_out =
deba@57:           arcs[(2 * e.id) | 1].next_out;
deba@57:       }
deba@57: 
deba@57:       if (nodes[n.id].first_out != -1) {
alpar@209:         arcs[nodes[n.id].first_out].prev_out = ((2 * e.id) | 1);
deba@57:       }
deba@57:       arcs[2 * e.id].target = n.id;
deba@57:       arcs[(2 * e.id) | 1].prev_out = -1;
deba@57:       arcs[(2 * e.id) | 1].next_out = nodes[n.id].first_out;
deba@57:       nodes[n.id].first_out = ((2 * e.id) | 1);
deba@57:     }
deba@57: 
deba@57:   };
deba@57: 
deba@57:   typedef GraphExtender<ListGraphBase> ExtendedListGraphBase;
deba@57: 
deba@57: 
kpeter@73:   /// \addtogroup graphs
deba@57:   /// @{
deba@57: 
kpeter@73:   ///A general undirected graph structure.
deba@57: 
kpeter@735:   ///\ref ListGraph is a versatile and fast undirected graph
kpeter@735:   ///implementation based on linked lists that are stored in
alpar@209:   ///\c std::vector structures.
deba@57:   ///
kpeter@735:   ///This type fully conforms to the \ref concepts::Graph "Graph concept"
kpeter@735:   ///and it also provides several useful additional functionalities.
kpeter@735:   ///Most of its member functions and nested classes are documented
kpeter@73:   ///only in the concept class.
kpeter@73:   ///
kpeter@787:   ///This class provides only linear time counting for nodes, edges and arcs.
kpeter@787:   ///
kpeter@73:   ///\sa concepts::Graph
kpeter@735:   ///\sa ListDigraph
deba@57:   class ListGraph : public ExtendedListGraphBase {
kpeter@617:     typedef ExtendedListGraphBase Parent;
kpeter@617: 
deba@57:   private:
kpeter@735:     /// Graphs are \e not copy constructible. Use GraphCopy instead.
deba@57:     ListGraph(const ListGraph &) :ExtendedListGraphBase()  {};
kpeter@735:     /// \brief Assignment of a graph to another one is \e not allowed.
kpeter@735:     /// Use GraphCopy instead.
deba@57:     void operator=(const ListGraph &) {}
deba@57:   public:
deba@57:     /// Constructor
alpar@209: 
deba@57:     /// Constructor.
deba@57:     ///
deba@57:     ListGraph() {}
deba@57: 
kpeter@73:     typedef Parent::OutArcIt IncEdgeIt;
deba@57: 
kpeter@73:     /// \brief Add a new node to the graph.
deba@57:     ///
kpeter@735:     /// This function adds a new node to the graph.
kpeter@559:     /// \return The new node.
deba@57:     Node addNode() { return Parent::addNode(); }
deba@57: 
kpeter@73:     /// \brief Add a new edge to the graph.
deba@57:     ///
kpeter@735:     /// This function adds a new edge to the graph between nodes
kpeter@735:     /// \c u and \c v with inherent orientation from node \c u to
kpeter@735:     /// node \c v.
kpeter@559:     /// \return The new edge.
kpeter@735:     Edge addEdge(Node u, Node v) {
kpeter@735:       return Parent::addEdge(u, v);
deba@57:     }
deba@234: 
kpeter@735:     ///\brief Erase a node from the graph.
deba@234:     ///
kpeter@787:     /// This function erases the given node along with its incident arcs
kpeter@787:     /// from the graph.
kpeter@787:     ///
kpeter@787:     /// \note All iterators referencing the removed node or the incident
kpeter@787:     /// edges are invalidated, of course.
kpeter@735:     void erase(Node n) { Parent::erase(n); }
kpeter@735: 
kpeter@735:     ///\brief Erase an edge from the graph.
deba@234:     ///
kpeter@735:     /// This function erases the given edge from the graph.
kpeter@787:     ///
kpeter@787:     /// \note All iterators referencing the removed edge are invalidated,
kpeter@787:     /// of course.
kpeter@735:     void erase(Edge e) { Parent::erase(e); }
deba@149:     /// Node validity check
deba@149: 
kpeter@735:     /// This function gives back \c true if the given node is valid,
kpeter@735:     /// i.e. it is a real node of the graph.
deba@149:     ///
kpeter@735:     /// \warning A removed node could become valid again if new nodes are
deba@149:     /// added to the graph.
deba@149:     bool valid(Node n) const { return Parent::valid(n); }
kpeter@735:     /// Edge validity check
kpeter@735: 
kpeter@735:     /// This function gives back \c true if the given edge is valid,
kpeter@735:     /// i.e. it is a real edge of the graph.
kpeter@735:     ///
kpeter@735:     /// \warning A removed edge could become valid again if new edges are
kpeter@735:     /// added to the graph.
kpeter@735:     bool valid(Edge e) const { return Parent::valid(e); }
deba@149:     /// Arc validity check
deba@149: 
kpeter@735:     /// This function gives back \c true if the given arc is valid,
kpeter@735:     /// i.e. it is a real arc of the graph.
deba@149:     ///
kpeter@735:     /// \warning A removed arc could become valid again if new edges are
deba@149:     /// added to the graph.
deba@149:     bool valid(Arc a) const { return Parent::valid(a); }
deba@149: 
kpeter@735:     /// \brief Change the first node of an edge.
deba@149:     ///
kpeter@735:     /// This function changes the first node of the given edge \c e to \c n.
deba@57:     ///
kpeter@735:     ///\note \c EdgeIt and \c ArcIt iterators referencing the
kpeter@735:     ///changed edge are invalidated and all other iterators whose
kpeter@735:     ///base node is the changed node are also invalidated.
kpeter@73:     ///
kpeter@73:     ///\warning This functionality cannot be used together with the
kpeter@73:     ///Snapshot feature.
deba@235:     void changeU(Edge e, Node n) {
deba@235:       Parent::changeU(e,n);
alpar@209:     }
kpeter@735:     /// \brief Change the second node of an edge.
deba@57:     ///
kpeter@735:     /// This function changes the second node of the given edge \c e to \c n.
deba@57:     ///
kpeter@735:     ///\note \c EdgeIt iterators referencing the changed edge remain
kpeter@786:     ///valid, but \c ArcIt iterators referencing the changed edge and
kpeter@735:     ///all other iterators whose base node is the changed node are also
kpeter@735:     ///invalidated.
kpeter@73:     ///
kpeter@73:     ///\warning This functionality cannot be used together with the
kpeter@73:     ///Snapshot feature.
deba@235:     void changeV(Edge e, Node n) {
deba@235:       Parent::changeV(e,n);
deba@57:     }
kpeter@735: 
deba@57:     /// \brief Contract two nodes.
deba@57:     ///
kpeter@735:     /// This function contracts the given two nodes.
kpeter@735:     /// Node \c b is removed, but instead of deleting
kpeter@735:     /// its incident edges, they are joined to node \c a.
kpeter@735:     /// If the last parameter \c r is \c true (this is the default value),
kpeter@735:     /// then the newly created loops are removed.
deba@57:     ///
kpeter@735:     /// \note The moved edges are joined to node \c a using changeU()
kpeter@735:     /// or changeV(), thus all edge and arc iterators whose base node is
kpeter@735:     /// \c b are invalidated.
kpeter@735:     /// Moreover all iterators referencing node \c b or the removed 
kpeter@735:     /// loops are also invalidated. Other iterators remain valid.
kpeter@73:     ///
kpeter@73:     ///\warning This functionality cannot be used together with the
kpeter@73:     ///Snapshot feature.
deba@57:     void contract(Node a, Node b, bool r = true) {
kpeter@73:       for(IncEdgeIt e(*this, b); e!=INVALID;) {
alpar@209:         IncEdgeIt f = e; ++f;
alpar@209:         if (r && runningNode(e) == a) {
alpar@209:           erase(e);
deba@235:         } else if (u(e) == b) {
deba@235:           changeU(e, a);
alpar@209:         } else {
deba@235:           changeV(e, a);
alpar@209:         }
alpar@209:         e = f;
deba@57:       }
deba@57:       erase(b);
deba@57:     }
deba@57: 
kpeter@735:     ///Clear the graph.
kpeter@735: 
kpeter@735:     ///This function erases all nodes and arcs from the graph.
kpeter@735:     ///
kpeter@787:     ///\note All iterators of the graph are invalidated, of course.
kpeter@735:     void clear() {
kpeter@735:       Parent::clear();
kpeter@735:     }
kpeter@617: 
kpeter@736:     /// Reserve memory for nodes.
kpeter@736: 
kpeter@736:     /// Using this function, it is possible to avoid superfluous memory
kpeter@736:     /// allocation: if you know that the graph you want to build will
kpeter@736:     /// be large (e.g. it will contain millions of nodes and/or edges),
kpeter@736:     /// then it is worth reserving space for this amount before starting
kpeter@736:     /// to build the graph.
kpeter@736:     /// \sa reserveEdge()
kpeter@736:     void reserveNode(int n) { nodes.reserve(n); };
kpeter@736: 
kpeter@736:     /// Reserve memory for edges.
kpeter@736: 
kpeter@736:     /// Using this function, it is possible to avoid superfluous memory
kpeter@736:     /// allocation: if you know that the graph you want to build will
kpeter@736:     /// be large (e.g. it will contain millions of nodes and/or edges),
kpeter@736:     /// then it is worth reserving space for this amount before starting
kpeter@736:     /// to build the graph.
kpeter@736:     /// \sa reserveNode()
kpeter@736:     void reserveEdge(int m) { arcs.reserve(2 * m); };
deba@57: 
kpeter@73:     /// \brief Class to make a snapshot of the graph and restore
kpeter@73:     /// it later.
deba@57:     ///
kpeter@73:     /// Class to make a snapshot of the graph and restore it later.
deba@57:     ///
deba@57:     /// The newly added nodes and edges can be removed
deba@57:     /// using the restore() function.
deba@57:     ///
kpeter@735:     /// \note After a state is restored, you cannot restore a later state, 
kpeter@735:     /// i.e. you cannot add the removed nodes and edges again using
kpeter@735:     /// another Snapshot instance.
kpeter@735:     ///
kpeter@735:     /// \warning Node and edge deletions and other modifications
kpeter@735:     /// (e.g. changing the end-nodes of edges or contracting nodes)
kpeter@735:     /// cannot be restored. These events invalidate the snapshot.
kpeter@786:     /// However, the edges and nodes that were added to the graph after
kpeter@735:     /// making the current snapshot can be removed without invalidating it.
deba@57:     class Snapshot {
deba@57:     protected:
deba@57: 
deba@57:       typedef Parent::NodeNotifier NodeNotifier;
deba@57: 
deba@57:       class NodeObserverProxy : public NodeNotifier::ObserverBase {
deba@57:       public:
deba@57: 
deba@57:         NodeObserverProxy(Snapshot& _snapshot)
deba@57:           : snapshot(_snapshot) {}
deba@57: 
deba@57:         using NodeNotifier::ObserverBase::attach;
deba@57:         using NodeNotifier::ObserverBase::detach;
deba@57:         using NodeNotifier::ObserverBase::attached;
alpar@209: 
deba@57:       protected:
alpar@209: 
deba@57:         virtual void add(const Node& node) {
deba@57:           snapshot.addNode(node);
deba@57:         }
deba@57:         virtual void add(const std::vector<Node>& nodes) {
deba@57:           for (int i = nodes.size() - 1; i >= 0; ++i) {
deba@57:             snapshot.addNode(nodes[i]);
deba@57:           }
deba@57:         }
deba@57:         virtual void erase(const Node& node) {
deba@57:           snapshot.eraseNode(node);
deba@57:         }
deba@57:         virtual void erase(const std::vector<Node>& nodes) {
deba@57:           for (int i = 0; i < int(nodes.size()); ++i) {
deba@57:             snapshot.eraseNode(nodes[i]);
deba@57:           }
deba@57:         }
deba@57:         virtual void build() {
deba@57:           Node node;
deba@57:           std::vector<Node> nodes;
alpar@209:           for (notifier()->first(node); node != INVALID;
deba@57:                notifier()->next(node)) {
deba@57:             nodes.push_back(node);
deba@57:           }
deba@57:           for (int i = nodes.size() - 1; i >= 0; --i) {
deba@57:             snapshot.addNode(nodes[i]);
deba@57:           }
deba@57:         }
deba@57:         virtual void clear() {
deba@57:           Node node;
alpar@209:           for (notifier()->first(node); node != INVALID;
deba@57:                notifier()->next(node)) {
deba@57:             snapshot.eraseNode(node);
deba@57:           }
deba@57:         }
deba@57: 
deba@57:         Snapshot& snapshot;
deba@57:       };
deba@57: 
deba@57:       class EdgeObserverProxy : public EdgeNotifier::ObserverBase {
deba@57:       public:
deba@57: 
deba@57:         EdgeObserverProxy(Snapshot& _snapshot)
deba@57:           : snapshot(_snapshot) {}
deba@57: 
deba@57:         using EdgeNotifier::ObserverBase::attach;
deba@57:         using EdgeNotifier::ObserverBase::detach;
deba@57:         using EdgeNotifier::ObserverBase::attached;
alpar@209: 
deba@57:       protected:
deba@57: 
kpeter@73:         virtual void add(const Edge& edge) {
kpeter@73:           snapshot.addEdge(edge);
deba@57:         }
kpeter@73:         virtual void add(const std::vector<Edge>& edges) {
kpeter@73:           for (int i = edges.size() - 1; i >= 0; ++i) {
kpeter@73:             snapshot.addEdge(edges[i]);
deba@57:           }
deba@57:         }
kpeter@73:         virtual void erase(const Edge& edge) {
kpeter@73:           snapshot.eraseEdge(edge);
deba@57:         }
kpeter@73:         virtual void erase(const std::vector<Edge>& edges) {
kpeter@73:           for (int i = 0; i < int(edges.size()); ++i) {
kpeter@73:             snapshot.eraseEdge(edges[i]);
deba@57:           }
deba@57:         }
deba@57:         virtual void build() {
kpeter@73:           Edge edge;
kpeter@73:           std::vector<Edge> edges;
alpar@209:           for (notifier()->first(edge); edge != INVALID;
kpeter@73:                notifier()->next(edge)) {
kpeter@73:             edges.push_back(edge);
deba@57:           }
kpeter@73:           for (int i = edges.size() - 1; i >= 0; --i) {
kpeter@73:             snapshot.addEdge(edges[i]);
deba@57:           }
deba@57:         }
deba@57:         virtual void clear() {
kpeter@73:           Edge edge;
alpar@209:           for (notifier()->first(edge); edge != INVALID;
kpeter@73:                notifier()->next(edge)) {
kpeter@73:             snapshot.eraseEdge(edge);
deba@57:           }
deba@57:         }
deba@57: 
deba@57:         Snapshot& snapshot;
deba@57:       };
kpeter@73: 
kpeter@73:       ListGraph *graph;
deba@57: 
deba@57:       NodeObserverProxy node_observer_proxy;
kpeter@73:       EdgeObserverProxy edge_observer_proxy;
deba@57: 
deba@57:       std::list<Node> added_nodes;
kpeter@73:       std::list<Edge> added_edges;
deba@57: 
deba@57: 
deba@57:       void addNode(const Node& node) {
alpar@209:         added_nodes.push_front(node);
deba@57:       }
deba@57:       void eraseNode(const Node& node) {
alpar@209:         std::list<Node>::iterator it =
deba@57:           std::find(added_nodes.begin(), added_nodes.end(), node);
deba@57:         if (it == added_nodes.end()) {
deba@57:           clear();
kpeter@73:           edge_observer_proxy.detach();
deba@57:           throw NodeNotifier::ImmediateDetach();
deba@57:         } else {
deba@57:           added_nodes.erase(it);
deba@57:         }
deba@57:       }
deba@57: 
kpeter@73:       void addEdge(const Edge& edge) {
alpar@209:         added_edges.push_front(edge);
deba@57:       }
kpeter@73:       void eraseEdge(const Edge& edge) {
alpar@209:         std::list<Edge>::iterator it =
kpeter@73:           std::find(added_edges.begin(), added_edges.end(), edge);
kpeter@73:         if (it == added_edges.end()) {
deba@57:           clear();
deba@57:           node_observer_proxy.detach();
deba@57:           throw EdgeNotifier::ImmediateDetach();
deba@57:         } else {
kpeter@73:           added_edges.erase(it);
kpeter@73:         }
deba@57:       }
deba@57: 
kpeter@73:       void attach(ListGraph &_graph) {
alpar@209:         graph = &_graph;
alpar@209:         node_observer_proxy.attach(graph->notifier(Node()));
kpeter@73:         edge_observer_proxy.attach(graph->notifier(Edge()));
deba@57:       }
alpar@209: 
deba@57:       void detach() {
alpar@209:         node_observer_proxy.detach();
alpar@209:         edge_observer_proxy.detach();
deba@57:       }
deba@57: 
deba@57:       bool attached() const {
deba@57:         return node_observer_proxy.attached();
deba@57:       }
deba@57: 
deba@57:       void clear() {
deba@57:         added_nodes.clear();
alpar@209:         added_edges.clear();
deba@57:       }
deba@57: 
deba@57:     public:
deba@57: 
deba@57:       /// \brief Default constructor.
deba@57:       ///
deba@57:       /// Default constructor.
kpeter@735:       /// You have to call save() to actually make a snapshot.
alpar@209:       Snapshot()
alpar@209:         : graph(0), node_observer_proxy(*this),
kpeter@73:           edge_observer_proxy(*this) {}
alpar@209: 
deba@57:       /// \brief Constructor that immediately makes a snapshot.
alpar@209:       ///
kpeter@735:       /// This constructor immediately makes a snapshot of the given graph.
kpeter@735:       Snapshot(ListGraph &gr)
alpar@209:         : node_observer_proxy(*this),
kpeter@73:           edge_observer_proxy(*this) {
kpeter@735:         attach(gr);
deba@57:       }
alpar@209: 
deba@57:       /// \brief Make a snapshot.
deba@57:       ///
kpeter@735:       /// This function makes a snapshot of the given graph.
kpeter@735:       /// It can be called more than once. In case of a repeated
deba@57:       /// call, the previous snapshot gets lost.
kpeter@735:       void save(ListGraph &gr) {
deba@57:         if (attached()) {
deba@57:           detach();
deba@57:           clear();
deba@57:         }
kpeter@735:         attach(gr);
deba@57:       }
alpar@209: 
deba@57:       /// \brief Undo the changes until the last snapshot.
kpeter@735:       ///
kpeter@735:       /// This function undos the changes until the last snapshot
kpeter@735:       /// created by save() or Snapshot(ListGraph&).
kpeter@740:       ///
kpeter@740:       /// \warning This method invalidates the snapshot, i.e. repeated
kpeter@740:       /// restoring is not supported unless you call save() again.
deba@57:       void restore() {
alpar@209:         detach();
alpar@209:         for(std::list<Edge>::iterator it = added_edges.begin();
kpeter@73:             it != added_edges.end(); ++it) {
alpar@209:           graph->erase(*it);
alpar@209:         }
alpar@209:         for(std::list<Node>::iterator it = added_nodes.begin();
deba@57:             it != added_nodes.end(); ++it) {
alpar@209:           graph->erase(*it);
alpar@209:         }
deba@57:         clear();
deba@57:       }
deba@57: 
kpeter@735:       /// \brief Returns \c true if the snapshot is valid.
deba@57:       ///
kpeter@735:       /// This function returns \c true if the snapshot is valid.
deba@57:       bool valid() const {
deba@57:         return attached();
deba@57:       }
deba@57:     };
deba@57:   };
alpar@209: 
alpar@209:   /// @}
deba@57: } //namespace lemon
alpar@209: 
deba@57: 
deba@57: #endif