all_simple_paths: List all simple paths from one source

Description

This function lists are simple paths from one source vertex to another
vertex or vertices. A path is simple if the vertices it visits are not
visited more than once.

The target vertex of vertices. Defaults to all vertices.

mode

Character constant, gives whether the shortest paths to or
from the given vertices should be calculated for directed graphs. If
out then the shortest paths from the vertex, if in
then to it will be considered. If all, the default, then
the corresponding undirected graph will be used, ie. not directed paths
are searched. This argument is ignored for undirected graphs.

Value

A list of integer vectors, each integer vector is a path from
the source vertex to one of the target vertices. A path is given by its
vertex ids.

Details

Note that potentially there are exponentially many paths between two
vertices of a graph, and you may run out of memory when using this
function, if your graph is lattice-like.

This function currently ignored multiple and loop edges.