Done day 25

diff --git a/advent25/Main.hs b/advent25/Main.hs
new file mode 100644 (file)
index 0000000..e5cedb9
--- /dev/null
+++ b/advent25/Main.hs
@@ -0,0 +1,47 @@
+-- Writeup at https://work.njae.me.uk/2024/12/25/advent-of-code-2024-day-23/
+
+import AoC
+
+import Data.List
+import Data.List.Split
+import Data.Char
+
+data Schematic = Lock [Int] | Key [Int]
+  deriving (Show, Eq, Ord)
+
+main :: IO ()
+main = 
+  do  dataFileName <- getDataFileName
+      text <- readFile dataFileName
+      let (locks, keys) = makeSchematics text
+      -- print locks
+      -- print keys
+      print $ part1 locks keys
+
+part1 :: [Schematic] -> [Schematic] -> Int
+part1 locks keys = length [(l, k) | l <- locks, k <- keys, compatible l k]
+
+compatible :: Schematic -> Schematic -> Bool
+compatible (Lock ls) (Key ks) = all (<= 5) $ zipWith (+) ls ks
+
+makeSchematics :: String -> ([Schematic], [Schematic])
+makeSchematics = partition isLock . fmap makeSchematic . splitTexts . lines
+  where isLock (Lock _) = True
+        isLock _ = False
+
+splitTexts :: [String] -> [[String]]
+splitTexts = splitOn [""]
+
+makeSchematic :: [String] -> Schematic
+makeSchematic ss
+  | isKeySchematic ss = Key $ heightsOf ss
+  | isLockSchematic ss = Lock $ heightsOf ss
+  | otherwise = error "Invalid schematic"
+
+isKeySchematic, isLockSchematic :: [String] -> Bool
+isKeySchematic  [a,_,_,_,_,_,b] = a == "....." && b == "#####"
+isLockSchematic [a,_,_,_,_,_,b] = a == "#####" && b == "....."
+
+heightsOf :: [String] -> [Int]
+heightsOf = fmap ((-1 +) . length . filter (== '#')) . transpose
+

diff --git a/adventofcode24.cabal b/adventofcode24.cabal
index d582171abda9ad8c4a7c9107a74b94a8549b867d..6fc716de2da50eab2b459ee9c6c27448cb80d7dc 100644 (file)
--- a/adventofcode24.cabal
+++ b/adventofcode24.cabal
@@ -222,4 +222,9 @@ executable advent23
 executable advent24
   import: warnings, common-extensions, build-directives, common-modules
   main-is: advent24/Main.hs
-  build-depends: attoparsec, text, containers
\ No newline at end of file
+  build-depends: attoparsec, text, containers
+
+executable advent25
+  import: warnings, common-extensions, build-directives, common-modules
+  main-is: advent25/Main.hs
+  build-depends: split
\ No newline at end of file