solution.pl

readFile(Path, Lines) :- open(Path, read, File), read_string(File, _, Str), split_string(Str, "\n", "\n", Lines).

main(R) :-
  readFile("input", Input),
  maplist(group, Input, Groups),
  /*flatten(Groups, Programs),
  connected(Programs, Groups, [0], Relations),
  sort(Relations, Uniques),*/
  connected([0], [], Groups, Uniques),
  length(Uniques, R), !.

part2(R) :-
  readFile("input", Input),
  maplist(group, Input, Groups),
  flatten(Groups, Programs),
  supergroups(Programs, Groups, 0, R), !.

/*connected([], _, R, R).
connected([H|T], Groups, X, R) :-
  member(H, X) -> connected(Groups, H, X1), connected(T, Groups, X1, R) ; connected(T, Groups, X, R).

connected([], R, R).
connected([H|T], X, R) :-
  member(Y, H), member(Y, X) -> flatten([H|X], X1), connected(T, X1, R) ; connected(T, X, R).*/
connected([], _, _, []).
connected([H|T], Visited, Groups, [H|R]):-
  select([H|Programs], Groups, NGroups),
  subtract(Programs, [H|Visited], NPrograms),
  union(T, NPrograms, NT),
  connected(NT, [H|Visited], NGroups, R).

supergroups([], _, Ac, Ac) :- !.
supergroups([N|Nodes], Groups, Ac, R)  :-
  connected([N], [], Groups, Cs),
  subtract(Nodes, Cs, NNodes),
  NAc is Ac+1,
  supergroups(NNodes, Groups, NAc, R).

group(Line, Result) :-
  split_string(Line, "<->", " <-> ", [ A, B ]),
  split_string(B, ", ", ", ", Bs),
  maplist(toInt, Bs, BsInt),
  toInt(A, AInt),
  Result = [ AInt | BsInt ].

toInt(String, Int) :- atom_codes(String, Code), number_codes(Int, Code).