60 lines
1.8 KiB
Haskell
60 lines
1.8 KiB
Haskell
{-# LANGUAGE LambdaCase #-}
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module Main where
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import Data.Functor
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import Data.List
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import Data.List.Split
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import Data.List.Extra hiding (split)
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import Debug.Trace
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data ℜ where
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None :: ℜ
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Num :: Int -> ℜ
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deriving Eq
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instance Show ℜ where
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show None = show '.'
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show (Num n) = show n
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parse :: String -> [ℜ]
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parse s = zip [0..] (trim s) >>= \(i,a) -> replicate (read [a]) (if even i then Num (i `div` 2) else None)
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sort1 :: [ℜ] -> [ℜ]
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sort1 s
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| None `notElem` s = s
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| otherwise = case last s of
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None -> sort1 $ init s
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n -> sort1 $ takeWhile (/= None) s ++ [n] ++ drop 1 (dropWhile (/= None) (init s))
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chunks :: [ℜ] -> [[ℜ]]
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chunks =
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init . foldr (\a (x:xs) -> if a `elem` x then (a:x):xs else [a]:x:xs) [[]]
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fit :: [[ℜ]] -> [ℜ] -> [ℜ]
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fit s t = let (p,a) = break (elem None) s
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(n,a') = span (elem None) a in
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if null n then concat s ++ t else
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concat p ++ if length (head n) >= length t then t ++ replicate (length n) None ++ concat a' else concat n ++ fit a' t
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sort2 :: [ℜ] -> [ℜ]
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sort2 s = let c = chunks s in
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if notElem None $ last c
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then let fitted = fit (init c) (last c) in
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if s == fitted then head c ++ case c of
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[] -> []
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[c] -> c
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c@[_,_] -> concat c
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c -> sort2 (concat . tail $ init c) ++ last c else sort2 fitted
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else sort2 (concat $ init c) ++ last c
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solve :: ([ℜ] -> [ℜ]) -> [ℜ] -> Int
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solve f s = let fixed = (\case
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Num n -> n
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None -> 0) <$> f s in
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sum $ zipWith (*) fixed [0..]
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main :: IO ()
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main = readFile "inputs/9.example" <&> parse >>= \i ->
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print (solve sort1 i) >>
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print (solve sort2 i)
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