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module Main where
import Data.List (sort)
isStartParen :: Char -> Bool
isStartParen '(' = True
isStartParen '[' = True
isStartParen '{' = True
isStartParen '<' = True
isStartParen _ = False
isEndParen :: Char -> Bool
isEndParen ')' = True
isEndParen ']' = True
isEndParen '}' = True
isEndParen '>' = True
isEndParen _ = False
flipParen :: Char -> Char
flipParen '(' = ')'
flipParen ')' = '('
flipParen '[' = ']'
flipParen ']' = '['
flipParen '{' = '}'
flipParen '}' = '{'
flipParen '<' = '>'
flipParen '>' = '<'
flipParen _ = undefined
getScore :: Char -> Int
getScore ')' = 3
getScore ']' = 57
getScore '}' = 1197
getScore '>' = 25137
completionScore :: Char -> Int
completionScore ')' = 1
completionScore ']' = 2
completionScore '}' = 3
completionScore '>' = 4
completionScore _ = undefined
consumeBlock :: Char -> String -> Either Char String
consumeBlock t "" = Right ""
consumeBlock t (c:cs) | c == flipParen t = Right cs
| isStartParen c = (consumeBlock c cs) >>= (consumeBlock t)
| otherwise = Left c
corruptionScore :: String -> Int
corruptionScore "" = 0
corruptionScore (c:cs) = case consumeBlock c cs of
Left c -> getScore c
Right s -> corruptionScore s
getCompletion :: String -> String -> String
getCompletion stack "" = map flipParen stack
getCompletion stack (c:cs) | isStartParen c = getCompletion (c : stack) cs
| otherwise = getCompletion (tail stack) cs
main :: IO ()
main = do
s <- readFile "./input"
let notCorrupted = filter ((== 0) . corruptionScore) (lines s)
let scores = sort $ map ((foldl (\acc x -> (acc * 5) + (completionScore x)) 0) . getCompletion "") notCorrupted
print $ scores !! (div (length scores) 2)
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