haskell: 2023 12 parse

2023/haskell/solutions/Day12.hs

@@ -0,0 +1,53 @@
+{-# LANGUAGE OverloadedStrings #-}
+module Day12 where
+
+import Data.Void (Void)
+import Data.Text (Text)
+import Text.Megaparsec (Parsec, errorBundlePretty, runParser, many, eof, choice, sepBy)
+import Data.Bifunctor (first)
+import Text.Megaparsec.Char (char, space, newline)
+import Text.Megaparsec.Char.Lexer (decimal)
+
+
+data Cell
+  = U -- ? unknown
+  | O -- . operational
+  | D -- # damaged
+  deriving Show
+
+type Row = ([Cell], [Int])
+
+type Parser = Parsec Void Text
+
+
+input :: Text
+input =
+  "???.### 1,1,3\n\
+  \.??..??...?##. 1,1,3\n\
+  \?#?#?#?#?#?#?#? 1,3,1,6\n\
+  \????.#...#... 4,1,1\n\
+  \????.######..#####. 1,6,5\n\
+  \?###???????? 3,2,1\n"
+
+parse :: Text -> Either String [Row]
+parse = first errorBundlePretty . runParser rows ""
+  where
+    cell :: Parser Cell
+    cell = choice [U <$ char '?', O <$ char '.', D <$ char '#']
+    row :: Parser Row
+    row = do
+      cs <- many cell <* space
+      ns <- decimal `sepBy` char ',' <* newline
+      return (cs, ns)
+    rows :: Parser [Row]
+    rows = many row <* eof
+
+arrange :: [Cell] -> [Int] -> [[Cell]]
+arrange = _
+
+solveA :: [Row] -> Int
+solveA = length . concatMap (uncurry arrange)
+
+-- >>> parse input
+-- Right [([U,U,U,O,D,D,D],[1,1,3]),([O,U,U,O,O,U,U,O,O,O,U,D,D,O],[1,1,3]),([U,D,U,D,U,D,U,D,U,D,U,D,U,D,U],[1,3,1,6]),([U,U,U,U,O,D,O,O,O,D,O,O,O],[4,1,1]),([U,U,U,U,O,D,D,D,D,D,D,O,O,D,D,D,D,D,O],[1,6,5]),([U,D,D,D,U,U,U,U,U,U,U,U],[3,2,1])]
+