d9

09/part2.pl

@@ -0,0 +1,12 @@
+start :-
+    input(Input),
+    findall(P, (member(L, Input), predict(L, P)), Ps),
+    sum_list(Ps, Answer),
+    writef('Answer=%t\n', [Answer]).
+
+predict(L, 0) :- maplist(=:=(0), L), !.
+predict(L, X) :-
+    L = [L1 | CdrL],
+    foldl([Li1, Li2, C, D]>>(Li2 is Li1 - C, D = Li1), L, [_ | NewL], 0, _),
+    predict(NewL, SubX),
+    X is L1 - SubX.