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module Main where
import Text.ParserCombinators.Parsec
import Data.List (sort)
import Control.Monad
data Direction = Upper | Lower
doHalving :: [Direction] -> (Int, Int) -> (Int, Int)
doHalving [] p = p
doHalving (Lower:rest) (l, u) = doHalving rest (l, (u+l) `div` 2)
doHalving (Upper:rest) (l, u) = doHalving rest ((u+l) `div` 2 + 1, u)
findId :: (Int, Int) -> Int
findId (row, col) = row * 8 + col
doValidate :: String -> Int
doValidate s = findId (row, col)
where row = fst $ flip doHalving (0, 127) $ map readDir (take 7 s)
col = fst $ flip doHalving (0, 7) $ map readDir (drop 7 s)
readDir :: Char -> Direction
readDir c
| c `elem` "FL" = Lower
| otherwise = Upper
main :: IO ()
main = do
n <- lines <$> readFile "input/05"
let valids = map doValidate n
ans1 = maximum valids
print ans1
print $ sum [minimum valids .. ans1] - sum valids
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