FAQ: I don’t get how you use recursion to free the entire family?

Perhaps look at the print_family function for inspiration. See how it takes in a person pointer p and then calls itself for p’s parents? That’s the same idea for free_family. In order to free a person, you have to free p’s parents. When you call free_family on the parent, that parent becomes “p” and the function runs again and again until there is no longer a p because there are no more ancestors in the tree. In our example with generations = 3, that means there are 7 people that should be freed.

D  E   F  G
  B     C
     A

we call free_family on A (which is stored in p) That then calls free_familyon B and on C (ie, the parent[0] and parent[1] of p).

So free_family(B) runs and calls free_family on B’s parents (ie, parent[0] and parent[1] of p. On B, that then recursively calls free_family on D and on E (ie, the parent[0] and parent[1] of p), and since D and E don’t have parents, the function frees p which is D, rewinds to where it left off (on E), frees E and keeps moving back down until we end up freeing every person.