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ArcLookUp< GR > Class Template Reference

Detailed Description

template<class GR>
class lemon::ArcLookUp< GR >

Using this class, you can find an arc in a digraph from a given source to a given target in time O(logd), where d is the out-degree of the source node.

It is not possible to find all parallel arcs between two nodes. Use AllArcLookUp for this purpose.

This class is static, so you should call refresh() (or at least refresh(Node)) to refresh this data structure whenever the digraph changes. This is a time consuming (superlinearly proportional (O(m logm)) to the number of arcs).
Template Parameters
GRThe type of the underlying digraph.
See Also

#include <lemon/core.h>

+ Inheritance diagram for ArcLookUp< GR >:

Public Types

typedef GR Digraph
 The Digraph type.

Public Member Functions

 ArcLookUp (const Digraph &g)
 Constructor. More...
void refresh (Node n)
 Refresh the search data structure at a node. More...
void refresh ()
 Refresh the full data structure. More...
Arc operator() (Node s, Node t) const
 Find an arc between two nodes. More...

Constructor & Destructor Documentation

ArcLookUp ( const Digraph g)


It builds up the search database, which remains valid until the digraph changes.

Member Function Documentation

void refresh ( Node  n)

Build up the search database of node n.

It runs in time O(d logd), where d is the number of the outgoing arcs of n.

void refresh ( )

Build up the full search database. In fact, it simply calls refresh(n) for each node n.

It runs in time O(m logD), where m is the number of the arcs in the digraph and D is the maximum out-degree of the digraph.

Arc operator() ( Node  s,
Node  t 
) const

Find an arc between two nodes in time O(logd), where d is the number of outgoing arcs of s.

sThe source node.
tThe target node.
An arc from s to t if there exists, INVALID otherwise.
If you change the digraph, refresh() must be called before using this operator. If you change the outgoing arcs of a single node n, then refresh(n) is enough.