# OpenGraph DrawingFramework

v. 2022.02 (Dogwood)

Orientations

Provides functions for orienting graphs like st-numbering. More...

## Functions

int ogdf::computeSTNumbering (const Graph &G, NodeArray< int > &numbering, node s=nullptr, node t=nullptr, bool randomized=false)
Computes an st-Numbering of G. More...

bool ogdf::isSTNumbering (const Graph &G, NodeArray< int > &st_no, int max)
Tests, whether a numbering of the nodes is an st-numbering. More...

## Detailed Description

Provides functions for orienting graphs like st-numbering.

## ◆ computeSTNumbering()

 int ogdf::computeSTNumbering ( const Graph & G, NodeArray< int > & numbering, node s = nullptr, node t = nullptr, bool randomized = false )

Computes an st-Numbering of G.

Precondition
G must be biconnected and simple, with the exception that the graph is allowed to have isolated nodes. If both s and t are set to nodes (both are not 0), they must be adjacent.
Parameters
 G is the input graph. numbering is assigned the st-number for each node. s is the source node for the st-numbering. t is the target node for the st-numbering. randomized is only used when both s and t are not set (both are 0); in this case a random edge (s,t) is chosen; otherwise the first node s with degree > 0 is chosen and its first neighbor is used as t.
Returns
the number assigned to t, or 0 if no st-numbering could be computed.

## ◆ isSTNumbering()

 bool ogdf::isSTNumbering ( const Graph & G, NodeArray< int > & st_no, int max )

Tests, whether a numbering of the nodes is an st-numbering.

Precondition
G must be biconnected and simple, with the exception that the graph is allowed to have isolated nodes.