d15

15/part1.pl

@@ -0,0 +1,27 @@
+:- use_module(library(pio)).
+:- use_module(library(clpfd)).
+:- initialization(main, main).
+
+main([FileName|_]) :-
+    input(FileName, Input),
+    hashes(Input, Hash),
+    writef('Answer=%t\n', [Hash]).
+
+hashes(Strs, Hash) :-
+    concurrent_maplist(reverse, Strs, RStrs),
+    concurrent_maplist(hash, RStrs, Hashes),
+    sum_list(Hashes, Hash).
+
+hash([], 0).
+hash([C|Str], Hash) :- hash(Str, Prev), Hash is (Prev + C)*17 mod 256.
+
+% Input stuff
+input(FileName, Input) :- phrase_from_file(string(Input), FileName).
+
+string([]) --> (eos; "\n"), !.
+string([Item|Items]) --> item(Item), string(Items).
+
+item([]) --> (","; "\n"; eos), !.
+item([C|Chars]) --> [C], item(Chars).
+
+eos([], []).