Quest 3: The Deepest Fit

I thought this was going to be the knapsack problem, but no.

import Control.Monad  
import Data.List.Split  
import qualified Data.Set as Set  
import qualified Data.Multiset as MSet  

part1, part2, part3 :: [Int] -> Int  
part1 = sum . Set.fromList  
part2 = sum . Set.take 20 . Set.fromList  
part3 = maximum . MSet.toCountMap . MSet.fromList  

main =  
  forM_  
    [ ("everybody_codes_e2025_q03_p1.txt", part1),  
      ("everybody_codes_e2025_q03_p2.txt", part2),  
      ("everybody_codes_e2025_q03_p3.txt", part3)  
    ]  
    $ \(input, solve) ->  
      readFile input >>= print . solve . map read . splitOn ","