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/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Copyright (C) 2003-2009

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#ifndef LEMON_LIST_GRAPH_H

#define LEMON_LIST_GRAPH_H

///\ingroup graphs

///\file

///\brief ListDigraph and ListGraph classes.

#include <lemon/core.h>

#include <lemon/error.h>

#include <lemon/bits/graph_extender.h>

#include <vector>

#include <list>

namespace lemon {

  class ListDigraphBase {

  protected:

    struct NodeT {

      int first_in, first_out;

      int prev, next;

    };

    struct ArcT {

      int target, source;

      int prev_in, prev_out;

      int next_in, next_out;

    };

    std::vector<NodeT> nodes;

    int first_node;

    int first_free_node;

    std::vector<ArcT> arcs;

    int first_free_arc;

  public:

    typedef ListDigraphBase Digraph;

    class Node {

      friend class ListDigraphBase;

    protected:

      int id;

      explicit Node(int pid) { id = pid;}

    public:

      Node() {}

      Node (Invalid) { id = -1; }

      bool operator==(const Node& node) const {return id == node.id;}

      bool operator!=(const Node& node) const {return id != node.id;}

      bool operator<(const Node& node) const {return id < node.id;}

    };

    class Arc {

      friend class ListDigraphBase;

    protected:

      int id;

      explicit Arc(int pid) { id = pid;}

    public:

      Arc() {}

      Arc (Invalid) { id = -1; }

      bool operator==(const Arc& arc) const {return id == arc.id;}

      bool operator!=(const Arc& arc) const {return id != arc.id;}

      bool operator<(const Arc& arc) const {return id < arc.id;}

    };

    ListDigraphBase()

      : nodes(), first_node(-1),

        first_free_node(-1), arcs(), first_free_arc(-1) {}

    int maxNodeId() const { return nodes.size()-1; }

    int maxArcId() const { return arcs.size()-1; }

    Node source(Arc e) const { return Node(arcs[e.id].source); }

    Node target(Arc e) const { return Node(arcs[e.id].target); }

    void first(Node& node) const {

      node.id = first_node;

    }

    void next(Node& node) const {

      node.id = nodes[node.id].next;

    }

    void first(Arc& arc) const {

      int n;

      for(n = first_node;

          n!=-1 && nodes[n].first_in == -1;

          n = nodes[n].next) {}

      arc.id = (n == -1) ? -1 : nodes[n].first_in;

    }

    void next(Arc& arc) const {

      if (arcs[arc.id].next_in != -1) {

        arc.id = arcs[arc.id].next_in;

      } else {

        int n;

        for(n = nodes[arcs[arc.id].target].next;

            n!=-1 && nodes[n].first_in == -1;

            n = nodes[n].next) {}

        arc.id = (n == -1) ? -1 : nodes[n].first_in;

      }

    }

    void firstOut(Arc &e, const Node& v) const {

      e.id = nodes[v.id].first_out;

    }

    void nextOut(Arc &e) const {

      e.id=arcs[e.id].next_out;

    }

    void firstIn(Arc &e, const Node& v) const {

      e.id = nodes[v.id].first_in;

    }

    void nextIn(Arc &e) const {

      e.id=arcs[e.id].next_in;

    }

    static int id(Node v) { return v.id; }

    static int id(Arc e) { return e.id; }

    static Node nodeFromId(int id) { return Node(id);}

    static Arc arcFromId(int id) { return Arc(id);}

    bool valid(Node n) const {

      return n.id >= 0 && n.id < static_cast<int>(nodes.size()) &&

        nodes[n.id].prev != -2;

    }

    bool valid(Arc a) const {

      return a.id >= 0 && a.id < static_cast<int>(arcs.size()) &&

        arcs[a.id].prev_in != -2;

    }

    Node addNode() {

      int n;

      if(first_free_node==-1) {

        n = nodes.size();

        nodes.push_back(NodeT());

      } else {

        n = first_free_node;

        first_free_node = nodes[n].next;

    bool valid(Node n) const { return Parent::valid(n); }

    /// Arc validity check

    /// This function gives back \c true if the given arc is valid,

    /// i.e. it is a real arc of the digraph.

    ///

    /// \warning A removed arc could become valid again if new arcs are

    /// added to the digraph.

    bool valid(Arc a) const { return Parent::valid(a); }

    /// Change the target node of an arc

    /// This function changes the target node of the given arc \c a to \c n.

    ///

    ///\note \c ArcIt and \c OutArcIt iterators referencing the changed

    ///arc remain valid, however \c InArcIt iterators are invalidated.

    ///

    ///\warning This functionality cannot be used together with the Snapshot

    ///feature.

    void changeTarget(Arc a, Node n) {

      Parent::changeTarget(a,n);

    }

    /// Change the source node of an arc

    /// This function changes the source node of the given arc \c a to \c n.

    ///

    ///\note \c InArcIt iterators referencing the changed arc remain

    ///valid, however \c ArcIt and \c OutArcIt iterators are invalidated.

    ///

    ///\warning This functionality cannot be used together with the Snapshot

    ///feature.

    void changeSource(Arc a, Node n) {

      Parent::changeSource(a,n);

    }

    /// Reverse the direction of an arc.

    /// This function reverses the direction of the given arc.

    ///\note \c ArcIt, \c OutArcIt and \c InArcIt iterators referencing

    ///the changed arc are invalidated.

    ///

    ///\warning This functionality cannot be used together with the Snapshot

    ///feature.

    void reverseArc(Arc a) {

      Node t=target(a);

      changeTarget(a,source(a));

      changeSource(a,t);

    }

    ///Contract two nodes.

    ///This function contracts the given two nodes.

    ///Node \c v is removed, but instead of deleting its

    ///incident arcs, they are joined to node \c u.

    ///If the last parameter \c r is \c true (this is the default value),

    ///then the newly created loops are removed.

    ///

    ///\note The moved arcs are joined to node \c u using changeSource()

    ///or changeTarget(), thus \c ArcIt and \c OutArcIt iterators are

    ///invalidated for the outgoing arcs of node \c v and \c InArcIt

    ///iterators are invalidated for the incomming arcs of \c v.

    ///Moreover all iterators referencing node \c v or the removed 

    ///loops are also invalidated. Other iterators remain valid.

    ///

    ///\warning This functionality cannot be used together with the Snapshot

    ///feature.

    void contract(Node u, Node v, bool r = true)

    {

      for(OutArcIt e(*this,v);e!=INVALID;) {

        OutArcIt f=e;

        ++f;

        if(r && target(e)==u) erase(e);

        else changeSource(e,u);

        e=f;

      }

      for(InArcIt e(*this,v);e!=INVALID;) {

        InArcIt f=e;

        ++f;

        if(r && source(e)==u) erase(e);

        else changeTarget(e,u);

        e=f;

      }

      erase(v);

    }

    ///Split a node.

    ///This function splits the given node. First, a new node is added

    ///to the digraph, then the source of each outgoing arc of node \c n

    ///is moved to this new node.

    ///If the second parameter \c connect is \c true (this is the default

    ///value), then a new arc from node \c n to the newly created node

    ///is also added.

    ///\return The newly created node.

    ///

    ///

    ///\warning This functionality cannot be used together with the

    ///Snapshot feature.

    Node split(Node n, bool connect = true) {

      Node b = addNode();

      }

      if (connect) addArc(n,b);

      return b;

    }

    ///Split an arc.

    ///This function splits the given arc. First, a new node \c v is

    ///added to the digraph, then the target node of the original arc

    ///is set to \c v. Finally, an arc from \c v to the original target

    ///is added.

    ///\return The newly created node.

    ///

    ///\note \c InArcIt iterators referencing the original arc are

    ///invalidated. Other iterators remain valid.

    ///

    ///\warning This functionality cannot be used together with the

    ///Snapshot feature.

    Node split(Arc a) {

      Node v = addNode();

      addArc(v,target(a));

      changeTarget(a,v);

      return v;

    }

    ///Clear the digraph.

    ///This function erases all nodes and arcs from the digraph.

    ///

    void clear() {

      Parent::clear();

    }

    /// Reserve memory for nodes.

    /// Using this function, it is possible to avoid superfluous memory

    /// allocation: if you know that the digraph you want to build will

    /// be large (e.g. it will contain millions of nodes and/or arcs),

    /// then it is worth reserving space for this amount before starting

    /// to build the digraph.

    /// \sa reserveArc()

    void reserveNode(int n) { nodes.reserve(n); };

    /// Reserve memory for arcs.

    /// Using this function, it is possible to avoid superfluous memory

    /// allocation: if you know that the digraph you want to build will

    /// be large (e.g. it will contain millions of nodes and/or arcs),

    /// then it is worth reserving space for this amount before starting

    /// to build the digraph.

    /// \sa reserveNode()

    void reserveArc(int m) { arcs.reserve(m); };

    /// \brief Class to make a snapshot of the digraph and restore

    /// it later.

    ///

    /// Class to make a snapshot of the digraph and restore it later.

    ///

    /// The newly added nodes and arcs can be removed using the

    /// restore() function.

    ///

    /// \note After a state is restored, you cannot restore a later state, 

    /// i.e. you cannot add the removed nodes and arcs again using

    /// another Snapshot instance.

    ///

    /// \warning Node and arc deletions and other modifications (e.g.

    /// reversing, contracting, splitting arcs or nodes) cannot be

    /// restored. These events invalidate the snapshot.

    /// However the arcs and nodes that were added to the digraph after

    /// making the current snapshot can be removed without invalidating it.

    class Snapshot {

    protected:

      typedef Parent::NodeNotifier NodeNotifier;

      class NodeObserverProxy : public NodeNotifier::ObserverBase {

      public:

        NodeObserverProxy(Snapshot& _snapshot)

          : snapshot(_snapshot) {}

        using NodeNotifier::ObserverBase::attach;

        using NodeNotifier::ObserverBase::detach;

        using NodeNotifier::ObserverBase::attached;

      protected:

        virtual void add(const Node& node) {

          snapshot.addNode(node);

        }

        virtual void add(const std::vector<Node>& nodes) {

          for (int i = nodes.size() - 1; i >= 0; ++i) {

            snapshot.addNode(nodes[i]);

          }

        }

        virtual void erase(const Node& node) {