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module Day2 where
import Data.List.NonEmpty (xor, fromList)
import Data.List.Split (splitOn)
import Text.Read (readMaybe)
import System.Environment (getArgs)
valid :: (Int, Int) -> Char -> String -> Bool
valid (lo, hi) c s = xor $ fromList [s!!lo == c, s!!hi == c]
parseHeader :: String -> (Int, Int, Char)
parseHeader s = (lo, hi, c)
where [range, (c:_)] = splitOn " " s
[lo, hi] = map (\x -> x - 1) $ map read $ splitOn "-" range
lineValid :: String -> Bool
lineValid s = valid (lo, hi) c pass
where [header, pass] = splitOn ": " s
(lo, hi, c) = parseHeader header
-- Usage: runghc --ghc-arg="-package split" 2b.hs inputs/day2
main :: IO ()
main = do
args <- getArgs;
content <- readFile $ head args;
let l = lines content;
let nums = filter lineValid l
putStrLn $ show $ length nums;
return ();
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