d12p2. It was actually good; swipl's memoization table just didn't work.

12/part1.pl

@@ -1,3 +1,4 @@
+% Usage: swipl part1.pl input.txt
 :- use_module(library(pio)).
 :- use_module(library(dcg/basics)).
 :- initialization(main, main).

12/part2.pl

@@ -0,0 +1,65 @@
+% Usage: swipl part2.pl input.txt
+:- use_module(library(pio)).
+:- use_module(library(dcg/basics)).
+:- initialization(main, main).
+
+test :- main(['test.txt']).
+
+main([FileName | _]) :-
+    input(FileName, Lines),
+    concurrent_maplist(resolve_repeated, Lines, Ns),
+    sum_list(Ns, Count),
+    writef('Res=%w\n', [Count]).
+    
+resolve_repeated(Line-Bads, N) :-
+    append([Line, [?], Line, [?], Line, [?], Line, [?], Line], L5),
+    append([Bads, Bads, Bads, Bads, Bads], B5),
+    abolish_private_tables, table(resolve/2),
+    resolve(L5-B5, N).
+
+% Bads is list of contiguous blocks of bad items in Xs; w/unks resolved in Y.
+resolve([]-[], 1).
+resolve([o|Xs]-Bads, Y) :- resolve(Xs-Bads, Y).
+resolve([?|Xs]-Bads, Y) :-
+    findall(N, (resolve([o|Xs]-Bads, N); resolve([#|Xs]-Bads, N)), Ys),
+    sum_list(Ys, Y).
+resolve([#|Xs]-[N|Bads], Y) :-
+    length(BadsUnks, N),
+    (   append(BadsUnks, [], [#|Xs]),
+        RemainingXs = []
+    ;   append(BadsUnks, [Next|RemainingXs], [#|Xs]), (Next = o; Next = ?)
+    ),
+    bads_or_unks(BadsUnks),
+    resolve(RemainingXs-Bads, Y).
+
+% List contains all bads or unks
+bads_or_unks([]).
+bads_or_unks([#|List]) :- bads_or_unks(List).
+bads_or_unks([?|List]) :- bads_or_unks(List).
+    
+% List contains exactly N bad items.
+nbads([], 0).
+nbads([#|List], N) :- N > 0, Remain is N - 1, nbads(List, Remain).
+
+processed_line(1, Line-Bads, NewLine-NewBads) :-
+    append(Line, [o], NewLine),
+    NewBads = Bads.
+
+% read input file into [(o;#;?)]-[list of bad runs]
+input(FileName, Lines) :- phrase_from_file(lines(Lines), FileName).
+
+lines([]) --> eos.
+lines([Status-Parity|Lines]) --> status(Status), parity(Parity), lines(Lines).
+
+status([]) --> " ".
+status([o]) --> all_dots, " ".
+status([o, #|Cdr]) --> all_dots, "#", status(Cdr).
+status([o, ?|Cdr]) --> all_dots, "?", status(Cdr).
+status([#|Cdr]) --> "#", status(Cdr).
+status([?|Cdr]) --> "?", status(Cdr).
+
+all_dots --> ".".
+all_dots --> ".", all_dots.
+
+parity([N]) --> number(N), ("\n"; eos).
+parity([N|Cdr]) --> number(N), ",", parity(Cdr).