Return the Lollipop Graph; K_m connected to P_n.
This is the Barbell Graph without the right barbell.
For m>1 and n>=0, the complete graph K_m is connected to the path P_n. The resulting m+n nodes are labelled 0,...,m-1 for the complete graph and m,...,m+n-1 for the path. The 2 subgraphs are joined via the edge (m-1,m). If n=0, this is merely a complete graph.
Node labels are the integers 0 to number_of_nodes - 1.
(This graph is an extremal example in David Aldous and Jim Fill’s etext on Random Walks on Graphs.)