From d5ee7282e9e80c07fe9f0fc2a31643edaeab39a5 Mon Sep 17 00:00:00 2001
From: Duy Truong <duytruong@google.com>
Date: Thu, 7 Dec 2023 15:04:57 -0800
Subject: [PATCH] shorten even more

---
 07/part2.pl | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/07/part2.pl b/07/part2.pl
index c444678..bad2b5b 100644
--- a/07/part2.pl
+++ b/07/part2.pl
@@ -1,18 +1,13 @@
 answer(Answer) :-
-    input(Input),
-    convert_input(Input, Hands, Bets),
+    input(Input), convert_input(Input, Hands, Bets),
     convlist(score, Hands, Scores),
     zip(Scores, Bets, ScoresBets),
-    sort(ScoresBets, SortedScoreBetsInv),
-    reverse(SortedScoreBetsInv, SortedScoreBets),
-    payout(SortedScoreBets, _, Answer).
-
-% payout([Hand-Bet], _, Payout) computes total payout from [Hand-Bet] map.
-payout([], 0, 0).
-payout([_-Bet | Cdr], Rank, Payout) :-
-    payout(Cdr, LastRank, LastPayout),
-    Rank is LastRank + 1,
-    Payout is LastPayout + Rank*Bet.
+    sort(ScoresBets, SortedScoreBets),
+    length(Input, NHands), length(VarList, NHands),
+    scanl([_, Prev, Curr]>>(Curr is Prev + 1), VarList, 0, [_ | Ranks]),
+    zip(Ranks, SortedScoreBets, RankScoreBets),
+    foldl([Rank-(_-Bet), Prev, Sum]>>(Sum is Prev + Rank*Bet),
+          RankScoreBets, 0, Answer).
 
 % score(Hand, Score) gets the score for one hand, that can be directly compared.
 score([A, B, C, D, E], Score) :-
@@ -47,8 +42,7 @@ card(84, 10). card(81, 12). card(75, 13). card(65, 14). % TQKA
 card(Char, Card) :- Char >= 48, Char =< 57, Card is Char - 48.
 
 % zip 2 lists into a map
-zip([], [], []).
-zip([A | ACdr], [B | BCdr], [A-B | ABCdr]) :- zip(ACdr, BCdr, ABCdr).
+zip(List1, List2, Map) :- maplist([A, B, A-B]>>(true), List1, List2, Map).
 
 % convert_input(InputList, Cards, Bets)
 convert_input([], [], []).