numbers_strings([], []).
numbers_strings([A|As], [B|Bs]) :-
    number_string(A, B),
    numbers_strings(As, Bs).

read_file(Stream, X) :-
    \+ at_end_of_stream(Stream),
    read_line_to_codes(Stream, C),
    string_chars(S, C),
    split_string(S, ",", "", Y),
    numbers_strings(X, Y),
    at_end_of_stream(Stream).

main :-
    open('../input/06', read, Stream),
    read_file(Stream, Lines), !,
    close(Stream),
    iterate_n(256, Lines, Res),
    length(Res, N),
    print(N).

tick_existing([], [], 0).
tick_existing([0|Xs], [6|Ys], New) :-
    tick_existing(Xs, Ys, New1),
    New is New1 + 1.
tick_existing([X|Xs], [Y|Ys], New) :-
    X > 0,
    tick_existing(Xs, Ys, New),
    Y is X - 1.
spawn_n(0, []).
spawn_n(N, [8|Ys]) :-
    N1 is N - 1,
    spawn_n(N1, Ys).
iterate(X, Y) :-
    tick_existing(X, Y0, New), !,
    spawn_n(New, Y1),
    append(Y0, Y1, Y), !.

iterate_n(0, X, X).
iterate_n(N, X, Y) :-
    N1 is N - 1,
    iterate(X, Y0), !,
    iterate_n(N1, Y0, Y), !.