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.

Warning

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

GR	The type of the underlying digraph.

See Also

DynArcLookUp

AllArcLookUp

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

Constructor & Destructor Documentation

ArcLookUp ( const Digraph &  g )

inline

Constructor.

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

Member Function Documentation

void refresh ( Node  n )

inline

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 ( )

inline

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

inline

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

Parameters

s	The source node.
t	The target node.

Returns

An arc from s to t if there exists, INVALID otherwise.

Warning

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.