day6: clean up

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

day6.hs

@@ -4,18 +4,13 @@ main :: IO ()
 main = do
   input <- readFile "day6.in"
   putStr "Q1: "
-  print $ q1 input
+  print $ parse 4 input
   putStr "Q2: "
-  print $ q2 input
+  print $ parse 14 input
 
-q1, q2 :: String -> Int
-q1 = length . parse 4
-q2 = length . parse 14
+group :: Int -> [Char] -> [[Char]]
+group _ [] = []
+group n xs = take n xs : group n (tail xs)
 
-parse :: Int -> String -> String
-parse n a = parse' n (splitAt n a)
-
-parse' :: Int -> (String, String) -> String
-parse' n (a, b)
-  | length (nub (drop (length a - n) a)) == n = a
-  | otherwise = parse' n (a ++ [head b], tail b)
+parse :: Int -> String -> Int
+parse n = (+ n) . length . takeWhile ((< n) . length) . map nub . group n