d4p1 and d4p2

04/part2.pl

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+:- table match/3.
+:- table sum/5.
+
+% match1(WinningNums, CardNums, NMatches)
+match1(_, [], 0).
+match1(Wins, [X|Nums], N) :- member(X, Wins), match1(Wins, Nums, N1), N is N1 + 1.
+match1(Wins, [X|Nums], N) :- \+ member(X, Wins), match1(Wins, Nums, N).
+
+match(Input, Nth, NMatches) :-
+    nth1(Nth, Input, [Wins|CardNums]),
+    match1(Wins, CardNums, NMatches).
+
+% sum(Cards, X, StuffToSum, Indices, Sum).
+sum(_, _, [], [0], 0).
+sum(Cards, X, [Element|Rest], [I,INext|IRest], Sum) :-
+    sum(Cards, X, Rest, [INext|IRest], SumOfRest),
+    Sum is Element + SumOfRest,
+    I is INext + 1,
+    match(Cards, I, NMatches_i), NMatches_i >= X - I.
+sum(Cards, X, [_|Rest], [I,INext|IRest], SumOfRest) :-
+    sum(Cards, X, Rest, [INext|IRest], SumOfRest),
+    I is INext + 1,
+    match(Cards, I, NMatches_i), NMatches_i < X - I.
+
+% Number of card X = Nx = 1 + sum(Ni*(matches(i) >= x-i), i=1->x-1)
+ncards([], []).
+ncards([_|RestOfCards], [Nx|NRest]) :-
+    length(RestOfCards, X_minus_1), X is X_minus_1 + 1,
+    ncards(RestOfCards, NRest),
+    reverse(RestOfCards, ReversedRestOfCards),
+    sum(ReversedRestOfCards, X, NRest, _, Nx_minus_1), Nx is Nx_minus_1 + 1.
+
+% this is a more normal sum of a list
+sum([], 0).
+sum([Element|Rest], Sum) :- sum(Rest, RestOfSum), Sum is Element + RestOfSum.
+
+all_scores(Input, Score) :-
+    reverse(Input, ReversedInput),
+    ncards(ReversedInput, CardCounts),
+    sum(CardCounts, Score).