Graphs are common. But you don't have to represent each edge as a pointer. For example you can represent them using (sparse) adjacency matrices. Or you can repr

Graphs are common. But you don't have to represent each edge as a pointer. For example you can represent them using (sparse) adjacency matrices. Or you can represent edges using a pointer in each direction (even for a directed graph) or some other data structure (as is commonly the case in triangle mesh data structures). Lots of options. Most do not require GC.