How to represent a strange graph in some data structure

Question

A simple way to represent a graph is with a data structure of the form:

{1:[2,3],
 2:[1,3],
 3:[1,2]}

Where the keys in this dictionary are nod

Answer 1

You could implement it as a basic graph with nodes and edges. In each node, store a list of edges. For each of those edges, store a mapping from that "entry" edge, to the valid exit edges.

I should point out that the image you posted isn't a graph, since A, F, and D do not connect to any nodes (unless they're just off-screen).