Add 2020 day 6

haskellAoC/src/Y2020/Day06.hs

@@ -0,0 +1,28 @@
+module Y2020.Day06 (y20day06) where
+
+import Data.List.Split
+import Data.List
+
+countUniques :: String -> Int
+countUniques input = uniq
+  where uniq = length $ group $ sort input'
+        input' = filter (/= '\n') input
+
+keepCommons :: [Char] -> [Char] -> [Char]
+keepCommons [] _ = []
+keepCommons _ [] = []
+keepCommons (x:xs) (y:ys)
+  | x == y = x:(keepCommons xs ys)
+  | x < y = keepCommons xs (y:ys)
+  | x > y = keepCommons (x:xs) ys
+
+countDups :: String -> Int
+countDups input = length $ dups
+  where (h:t) = map sort $ lines input
+        dups = foldl keepCommons h t
+
+y20day06 :: [String] -> (String, String)
+y20day06 input = (part1, part2)
+  where part1 = show $ sum $ map countUniques groups
+        part2 = show $ sum $ map countDups groups
+        groups = splitOn "\n\n" $ unlines input

haskellAoC/src/Y2020/Days.hs

@@ -5,6 +5,7 @@ import Y2020.Day02
 import Y2020.Day03
 import Y2020.Day04
 import Y2020.Day05
+import Y2020.Day06
 
 
 year2020 :: String -> [String] -> (String, String)
@@ -13,3 +14,4 @@ year2020 "02" = y20day02
 year2020 "03" = y20day03
 year2020 "04" = y20day04
 year2020 "05" = y20day05
+year2020 "06" = y20day06