day12 part 1

part 2 is uhhhh

2023/day12/day12.hs

@@ -0,0 +1,40 @@
+import Control.Arrow
+import Control.Monad
+import Data.List
+
+main :: IO ()
+main = interact $ show . day12 . map parse . lines
+
+parse :: String -> (String, [Int])
+parse = second (read . ('[' :) . (++ "]") . tail) . break (== ' ')
+
+day12 :: [(String, [Int])] -> Int
+day12 = sum . map (length . genArrangements)
+
+part2ify :: (String, [Int]) -> (String, [Int])
+part2ify (s, xs) = (intercalate "?" $ replicate 5 s, concat $ replicate 5 xs)
+
+genMin :: [Int] -> [String]
+genMin = foldr (\x -> (:) (replicate x '#' ++ ".")) []
+
+genDots :: Int -> Int -> [[Int]]
+genDots n x = filter (\xs -> sum xs == x) $ replicateM n [0 .. x]
+
+buildMaxeds :: [String] -> [[Int]] -> [String]
+buildMaxeds ss = map (build ss)
+
+build :: [String] -> [Int] -> String
+build [] [x] = replicate x '.'
+build (s:ss) (x:xs) = replicate x '.' ++ s ++ build ss xs
+
+genArrangements :: (String, [Int]) -> [String]
+genArrangements (s, xs) = filter f $ buildMaxeds (genMin xs) (genDots w l)
+  where
+    f x = and (zipWith wEq s x)
+    w = succ $ length xs
+    l = length s - sum xs - pred (length xs)
+
+wEq :: Char -> Char -> Bool
+wEq _ '?' = True
+wEq '?' _ = True
+wEq c1 c2 = c1 == c2

2023/day12/testinput

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+???.### 1,1,3
+.??..??...?##. 1,1,3
+?#?#?#?#?#?#?#? 1,3,1,6
+????.#...#... 4,1,1
+????.######..#####. 1,6,5
+?###???????? 3,2,1