strongly_connected_components in c_graphs

[ncohen]

The function strongly_connected_components uses Networkx for the moment. As c_graphs are to become the standard implementation of graphs in Sage, this function should be rewritten in Cython.

This functions should be able to return two types of data :

• A list of lists : as the function connected_components
• A digraph whose vertices are [immutable Sets representing a set of vertices defining a strongly connected components] and such that there is an edge between A and B if there is an arc from one vertex of A to one vertex of B.

This because, the graph strongly connected components is acyclic, which is sometimes useful.

Nathann

[ncohen]

Done here, with small other things :-)

Nathann

[rlm]

Typo: "conaitning"

[rlm]

All tests pass. Works for me, if the typo gets fixed

[ncohen]

Done !