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- import Data.List
-
-
- main :: IO ()
- main = do
- input <- readFile "input"
- putStrLn . formatOutput . both (sum . map length) . groups . map lines . dlfsplit $ input
-
-
- formatOutput :: Show a => (a, a) -> String
- formatOutput (part1,part2) = "Part 1: " ++ show part1 ++ "\nPart 2: " ++ show part2
-
- -- Collect each group's answers
- groups :: (Foldable t, Eq a) => [t [a]] -> ([[a]], [[a]])
- groups [] = ([],[])
- groups (g:gs) = (foldr1 union g : unions, foldr1 intersect g : intersections)
- where (unions, intersections) = groups gs
-
- -- Split a string into a list across all the double newlines in it
- dlfsplit :: String -> [String]
- dlfsplit str = a : case b of
- [] -> []
- b -> dlfsplit b
- where (a,b) = dlfsplitonce str
-
- -- Split a string into two across the first double newline found
- dlfsplitonce :: String -> (String, String)
- dlfsplitonce [] = ([], [])
- dlfsplitonce (ca:cb:rest)
- | ca == '\n' && cb == '\n' = ([], rest)
- | otherwise = (ca:before, after)
- where (before, after) = dlfsplitonce (cb : rest)
- dlfsplitonce c = (c, [])
-
- -- Apply a function to both parts of a pair
- both :: (a -> b) -> (a, a) -> (b, b)
- both f (a,b) = (f a, f b)
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