2023 day 7: add Haskell solution

.gitignore

@@ -2,8 +2,8 @@
 *.o
 *.hi
 *data*.txt
-main
-main-[0-9]
+[Mm]ain
+[Mm]ain-[0-9]
 
 # Nix stuff
 result*

2023/7/Main.hs

@@ -0,0 +1,28 @@
+import Data.Bifunctor (second)
+import Data.List (group, sort, sortOn)
+import qualified Data.HashMap.Strict as HMS
+
+cardOrder :: HMS.HashMap Char Int
+cardOrder = HMS.fromList $ zip "AKQT98765432J" [0..]
+
+getWorth :: String -> [Int]
+getWorth cards = handType : map (cardOrder HMS.!) cards
+  where
+    noJs = filter (/= 'J') cards
+    jCount = 5 - length noJs
+    groupedCards = map length $ group $ sort noJs
+    handType = case length groupedCards of
+      0 -> 1
+      1 -> 1
+      2 -> if minimum groupedCards == 1 then 2 else 3
+      3 -> if maximum groupedCards + jCount == 3 then 4 else 5
+      4 -> 6
+      5 -> 7
+
+solve :: [String] -> Int
+solve = sum . zipWith (*) [1..] . map snd . sortOn (map negate . getWorth . fst) . map parseLine
+  where
+    parseLine = second read . splitAt 5
+
+main :: IO ()
+main = print . solve . lines =<< readFile "data.txt"