Day 25, Part 1

src/Day25.hs

@@ -0,0 +1,32 @@
+{-# OPTIONS_GHC -Wno-x-partial #-}
+
+module Day25 (day25_1) where
+
+import Control.Monad (guard)
+import Data.List (transpose)
+import Data.List.Split (splitOn)
+
+parseSchematics :: [String] -> [Int]
+parseSchematics s =
+  let s' = transpose . init $ tail s
+   in map (length . filter (== '#')) s'
+
+keyLockCombinations :: [[Int]] -> [[Int]] -> [[Int]]
+keyLockCombinations keys locks = do
+  key <- keys
+  lock <- locks
+
+  guard $ all (< 6) $ zipWith (+) key lock
+
+  return $ zipWith (+) key lock
+
+day25_1 :: IO ()
+day25_1 = do
+  contents <- lines <$> readFile "input/day25.txt"
+  let schematics = splitOn [""] contents
+      locks = map parseSchematics $ filter (\x -> head x == "#####" && last x == ".....") schematics
+      keys = map parseSchematics $ filter (\x -> head x == "....." && last x == "#####") schematics
+  putStrLn $
+    "Day 25, Puzzle 1 solution: "
+      ++ show (length $ keyLockCombinations keys locks)
+  print . length $ keyLockCombinations keys locks