py3: avoid sorting vertices and edges in method treewidth

[dcoudert]

We avoid sorting vertices, edges and connected components. The code is better this way, and this fixes a doctest error with py3.

CC: @tscrim @fchapoton

Component: graph theory

Author: David Coudert

Branch/Commit: f830eb9

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/27009

[dcoudert]

Commit: f830eb9

[dcoudert]

New commits:

f830eb9

trac #27009: avoid sorting in method treewidth

[dcoudert]

Branch: public/27009_treewidth

[tscrim]

comment:2

Why do you use for v in G.vertices(sort=False): instead of one of the iterators?

Other than that LGTM.

[dcoudert]

comment:3

The graph is modified inside the loop over all vertices, so I cannot use an iterator here (at least it's safer this way).
So we can use either G.vertices(sort=False) or list(G).

[tscrim]

comment:4

Okay, thanks for the explanation. LGTM.

[tscrim]

Reviewer: Travis Scrimshaw