Ugly day 6 solution

src/Day6.hs

@@ -0,0 +1,37 @@
+module Day6 (
+  findMarker,
+  findMarker',
+  findStart,
+  isUnique,
+  day6
+) where
+
+findMarker :: String -> Maybe Int
+findMarker = findMarker' 4 0 ""
+
+findStart :: String -> Maybe Int
+findStart = findMarker' 14 0 ""
+
+findMarker' :: Int -> Int -> String -> String -> Maybe Int
+findMarker' windowSize offset window  []
+  | isUnique window && length window == windowSize = Just offset
+  | otherwise = Nothing
+findMarker' windowSize offset window (c:cs)
+  | length window < windowSize = findMarker' windowSize (offset + 1) (c:window) cs
+  | not (isUnique window) = findMarker' windowSize (offset + 1) (c:init window) cs
+  | isUnique window = Just offset
+  | otherwise = Nothing
+
+
+isUnique :: (Eq a) => [a] -> Bool
+isUnique [] = True
+isUnique (c:cs) = c `notElem` cs && isUnique cs
+
+day6 :: IO ()
+day6 = do
+   input <- readFile "ressources/day06-input"
+   putStrLn "Day6"
+   let offset = findMarker input
+   putStrLn ("Found end marker at " ++ show offset)
+   let startOffset = findStart input
+   putStrLn ("Found start marker at " ++ show startOffset)

src/Lib.hs

@@ -7,6 +7,7 @@ import Day2
 import Day3
 import Day4
 import Day5
+import Day6
 
 someFunc :: IO ()
 someFunc = do
@@ -19,5 +20,7 @@ someFunc = do
   day4
   putStrLn "-----------"
   day5
+  putStrLn "-----------"
+  day6