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kpeter (Peter Kovacs)
kpeter@inf.elte.hu
Much better implementation for node splitting (#311) in ListDigraph. This solution is the same as the one that is used in SmartDigraph. It is much faster and does not invalidate any iterator like the former implementation.
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1 file changed with 9 insertions and 7 deletions:
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Ignore white space 48 line context
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@@ -11,93 +11,97 @@
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 * precise terms see the accompanying LICENSE file.
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 *
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 * This software is provided "AS IS" with no warranty of any kind,
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 * express or implied, and with no claim as to its suitability for any
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 * purpose.
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 *
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 */
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#ifndef LEMON_LIST_GRAPH_H
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#define LEMON_LIST_GRAPH_H
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///\ingroup graphs
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///\file
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///\brief ListDigraph and ListGraph classes.
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#include <lemon/core.h>
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#include <lemon/error.h>
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#include <lemon/bits/graph_extender.h>
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#include <vector>
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#include <list>
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namespace lemon {
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  class ListDigraph;
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  class ListDigraphBase {
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  protected:
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    struct NodeT {
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      int first_in, first_out;
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      int prev, next;
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    };
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    struct ArcT {
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      int target, source;
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      int prev_in, prev_out;
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      int next_in, next_out;
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    };
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    std::vector<NodeT> nodes;
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    int first_node;
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    int first_free_node;
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    std::vector<ArcT> arcs;
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    int first_free_arc;
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  public:
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    typedef ListDigraphBase Digraph;
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    class Node {
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      friend class ListDigraphBase;
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      friend class ListDigraph;
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    protected:
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      int id;
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      explicit Node(int pid) { id = pid;}
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    public:
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      Node() {}
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      Node (Invalid) { id = -1; }
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      bool operator==(const Node& node) const {return id == node.id;}
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      bool operator!=(const Node& node) const {return id != node.id;}
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      bool operator<(const Node& node) const {return id < node.id;}
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    };
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    class Arc {
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      friend class ListDigraphBase;
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      friend class ListDigraph;
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    protected:
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      int id;
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      explicit Arc(int pid) { id = pid;}
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    public:
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      Arc() {}
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      Arc (Invalid) { id = -1; }
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      bool operator==(const Arc& arc) const {return id == arc.id;}
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      bool operator!=(const Arc& arc) const {return id != arc.id;}
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      bool operator<(const Arc& arc) const {return id < arc.id;}
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    };
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    ListDigraphBase()
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      : nodes(), first_node(-1),
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        first_free_node(-1), arcs(), first_free_arc(-1) {}
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    int maxNodeId() const { return nodes.size()-1; }
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    int maxArcId() const { return arcs.size()-1; }
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    Node source(Arc e) const { return Node(arcs[e.id].source); }
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@@ -446,60 +450,58 @@
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        if(r && target(e)==u) erase(e);
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        else changeSource(e,u);
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        e=f;
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      }
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      for(InArcIt e(*this,v);e!=INVALID;) {
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        InArcIt f=e;
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        ++f;
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        if(r && source(e)==u) erase(e);
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        else changeTarget(e,u);
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        e=f;
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      }
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      erase(v);
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    }
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    ///Split a node.
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    ///This function splits the given node. First, a new node is added
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    ///to the digraph, then the source of each outgoing arc of node \c n
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    ///is moved to this new node.
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    ///If the second parameter \c connect is \c true (this is the default
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    ///value), then a new arc from node \c n to the newly created node
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    ///is also added.
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    ///\return The newly created node.
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    ///
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    ///\note \c ArcIt and \c OutArcIt iterators referencing the outgoing
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    ///arcs of node \c n are invalidated. Other iterators remain valid.
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    ///\note All iterators remain valid.
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    ///
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    ///\warning This functionality cannot be used together with the
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    ///Snapshot feature.
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    Node split(Node n, bool connect = true) {
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      Node b = addNode();
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      for(OutArcIt e(*this,n);e!=INVALID;) {
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        OutArcIt f=e;
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        ++f;
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        changeSource(e,b);
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        e=f;
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      nodes[b.id].first_out=nodes[n.id].first_out;
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      nodes[n.id].first_out=-1;
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      for(int i=nodes[b.id].first_out; i!=-1; i=arcs[i].next_out) {
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        arcs[i].source=b.id;
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      }
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      if (connect) addArc(n,b);
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      return b;
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    }
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    ///Split an arc.
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    ///This function splits the given arc. First, a new node \c v is
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    ///added to the digraph, then the target node of the original arc
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    ///is set to \c v. Finally, an arc from \c v to the original target
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    ///is added.
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    ///\return The newly created node.
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    ///
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    ///\note \c InArcIt iterators referencing the original arc are
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    ///invalidated. Other iterators remain valid.
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    ///
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    ///\warning This functionality cannot be used together with the
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    ///Snapshot feature.
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    Node split(Arc a) {
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      Node v = addNode();
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      addArc(v,target(a));
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      changeTarget(a,v);
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      return v;
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    }
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