68 lines
2.2 KiB
Haskell
68 lines
2.2 KiB
Haskell
import Control.Applicative
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import Control.Monad
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import Data.Char
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import Data.Functor
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import Data.List
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import Data.List.Extra (stripSuffix)
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import Data.List.Split
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import Data.Maybe
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import Text.Read
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import Data.Set (Set, fromList, isSubsetOf)
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data Attr = Byr | Iyr | Eyr | Hgt | Hcl | Ecl | Pid | Cid
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deriving (Show, Bounded, Enum, Eq, Ord)
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intval :: Int -> Int -> Int -> Maybe Int
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intval lo hi n = guard (lo <= n && n <= hi) $> n
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nDigits :: Int -> String -> Maybe String
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nDigits n s = guard (length s == n && all isDigit s) $> s
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hexColor :: String -> Maybe String
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hexColor s = guard (length s == 7 && s !! 0 == '#' && all (flip elem "0123456789abcdef") (drop 1 s)) $> s
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validEcl :: String -> Bool
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validEcl = flip elem ["amb", "blu", "brn", "gry", "grn", "hzl", "oth"]
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parseAttr :: String -> Maybe Attr
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parseAttr s =
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case splitOn ":" s of
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[key, value] -> case key of
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"byr" -> (readMaybe value >>= intval 1920 2002) $> Byr
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"iyr" -> (readMaybe value >>= intval 2010 2020) $> Iyr
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"eyr" -> (readMaybe value >>= intval 2020 2030) $> Eyr
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"hgt" ->
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let inch = stripSuffix "cm" value >>= readMaybe >>= intval 150 193 in
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let cm = stripSuffix "in" value >>= readMaybe >>= intval 59 76 in
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(inch <|> cm) $> Hgt
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"hcl" -> hexColor value $> Hcl
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"ecl" -> if validEcl value then Just Ecl else Nothing
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"pid" -> nDigits 9 value $> Pid
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"cid" -> Just Cid
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_ -> Nothing
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_ -> Nothing
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processLine :: String -> Maybe [Attr]
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processLine = mapM parseAttr . splitOn " "
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requiredAttrs :: Set Attr
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requiredAttrs = fromList $ enumFromTo Byr Pid
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combineAttrs :: [Attr] -> Maybe [Attr]
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combineAttrs attrs = guard (isSubsetOf requiredAttrs $ fromList $ attrs) $> attrs
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processPassport :: [String] -> Maybe [Attr]
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processPassport = combineAttrs . concat <=< mapM processLine
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processLines :: [String] -> [Maybe [Attr]]
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processLines = map processPassport . splitWhen (== "")
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countValid :: [Maybe [Attr]] -> Int
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countValid = length . filter isJust
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main :: IO ()
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main = do
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content <- readFile "4.txt"
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let valid = countValid $ processLines $ lines content
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print valid
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