Day eleven, but correct

day-11-haskell/day11-haskell.cabal

@@ -26,6 +26,7 @@ library
   ghc-options: -Wall -Wcompat -Widentities -Wincomplete-record-updates -Wincomplete-uni-patterns -Wmissing-home-modules -Wpartial-fields -Wredundant-constraints
   build-depends:
       base >=4.7 && <5
+    , containers
     , flow
   default-language: Haskell2010
 

day-11-haskell/package.yaml

@@ -24,6 +24,7 @@ library:
   source-dirs: src
   dependencies:
   - flow
+  - containers
 
 executables:
   day11-haskell-exe:

day-11-haskell/src/Lib.hs

@@ -1,13 +1,14 @@
 module Lib (task1, task2) where
 
 import Control.Monad (join)
+import qualified Data.Map.Strict as Map
 import Flow
 
 task1 :: String -> Int
-task1 input = parse input |> recurse blink 25 |> length
+task1 input = parse input |> map (\stone -> (stone, 1)) |> recurse blink 25 |> map (\(_, cnt) -> cnt) |> sum
 
 task2 :: String -> Int
-task2 input = parse input |> recurse blink 75 |> length
+task2 input = parse input |> map (\stone -> (stone, 1)) |> recurse blink 75 |> map (\(_, cnt) -> cnt) |> sum
 
 parse :: String -> [Int]
 parse input = words input |> map read
@@ -15,14 +16,15 @@ parse input = words input |> map read
 recurse :: (a -> a) -> Int -> a -> a
 recurse fun count start = iterate fun start !! count
 
-blink :: [Int] -> [Int]
-blink stones = map blinkItem stones |> join
+blink :: [(Int, Int)] -> [(Int, Int)]
+blink stones = map (\(stone, mult) -> blinkItem stone |> map (\s -> (s, mult))) stones |> join |> Map.fromListWith (+) |> Map.toList
 
 blinkItem :: Int -> [Int]
 blinkItem 0 = [1]
-blinkItem number = let digits = show number |> map (read . pure) :: [Int]
-                   in if length digits `mod` 2 == 0
-                      then case splitAt (length digits `div` 2) digits of
-                        (first, second) -> [map show first |> join |> read, map show second |> join |> read]
+blinkItem number = let str = show number
+                   in if length str `mod` 2 == 0
+                      then case splitAt (length str `div` 2) str of
+                        (first, second) -> [read first, read second]
                       else [number * 2024]
 
+