11 part 1 done

app/11.hs

@@ -2,11 +2,33 @@
 module Main where
 
 import Data.Functor
+import Data.List.Split
 
-parse = undefined
+parse :: String -> [Int]
+parse = (read <$>) . words
 
-solve1 = undefined
+rules :: [(Int -> Bool, Int -> [Int])]
+rules =
+  [
+   ((==0), const [1])
+  ,(even . length . show, \a -> let b = show a; s = length b in chunksOf (s `div` 2) b <&> read)
+  ,(const otherwise, pure . (*2024))
+  ]
 
+applyRule :: Int -> [Int]
+applyRule i = head . filter (/= mempty) $ rules >>= \(f,g) -> if f i then pure $ g i else pure mempty
+
+step :: [Int] -> [Int]
+step = (applyRule =<<)
+
+applyAmount :: Int -> a -> (a -> a) -> a
+applyAmount 0 a _ = a
+applyAmount n a f = f $ applyAmount (n-1) a f
+
+solve1 :: [Int] -> Int
+solve1 = length . flip (applyAmount 25) step
+
+solve2 :: [Int] -> Int
 solve2 = undefined
 
 main :: IO ()

inputs/11

@@ -0,0 +1 @@
+3279 998884 1832781 517 8 18864 28 0