advent2022

commit ceba7e7870ce19112262f75caae9ae9437a8c39f
parent 66665329bede75b8ab7bd11fed7b6b99b52588c2
Author: Decay <decay@todayiwilllaunchmyinfantsonintoorbit.com>
Date:   Mon,  5 Dec 2022 23:51:21 -0800

Day six in Prolog

Runs like dogshit but works. Takes around 30 seconds to yield an answer
to the second puzzle on a 2018 laptop.

Diffstat:
A
6/six.pl
 | 
33
+++++++++++++++++++++++++++++++++

1 file changed, 33 insertions(+), 0 deletions(-)
diff --git a/6/six.pl b/6/six.pl
@@ -0,0 +1,33 @@
+puzzle_data(File, Chars) :-
+    setup_call_cleanup(open(File, read, In),
+                       stream_input_chars(In, Chars),
+                       close(In)).
+stream_input_chars(In, Chars) :-
+    read_string(In, _, Str),
+    string_chars(Str, Chars).
+
+nFromHead(_, 0, _, []).
+nFromHead([H|_], 1, _, [H]).
+nFromHead([H|T], N, MaxN, [H|RT]) :- nFromHead(T, X, MaxN, RT),
+                                     N is X + 1,
+                                     MaxN >= N.
+nFromHead([H|T], N, [H|RT]) :- nFromHead(T, N, N, RT).
+
+allUnique([]).
+allUnique([_]).
+allUnique([H|T]) :- \+(member(H, T)),
+                    allUnique(T).
+
+fourUnequal([H|Rest], 4) :- nFromHead([H|Rest], 4, FirstFour),
+                            allUnique(FirstFour).
+fourUnequal([_|Rest], Pos) :- fourUnequal(Rest, X), Pos is X + 1.
+
+fourteenUnequal([H|Rest], 14) :- nFromHead([H|Rest], 14, FirstFourteen),
+                                 allUnique(FirstFourteen).
+fourteenUnequal([_|Rest], Pos) :- fourteenUnequal(Rest, X), Pos is X + 1.
+
+firstStar(N) :- puzzle_data("input", Chars),
+                fourUnequal(Chars, N).
+
+secondStar(N) :- puzzle_data("input", Chars),
+                 fourteenUnequal(Chars, N).