55 lines
1.4 KiB
Haskell
55 lines
1.4 KiB
Haskell
module Main where
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import Data.List (uncons)
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import Data.Maybe (mapMaybe)
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import Data.Set (Set)
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import Data.Set qualified as S
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import System.Environment (getArgs)
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main :: IO ()
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main = do
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input <- maybe (error "Missing argument to input file") (readFile . fst) =<< uncons <$> getArgs
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putStrLn $ unwords ["Part 1:", show $ part1 input]
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putStrLn $ unwords ["Part 2:", show $ part2 input]
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area :: (Int, Int) -> (Int, Int) -> Int
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area (x1, y1) (x2, y2) = x' * y'
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where
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x' = max x1 x2 - min x1 x2 + 1
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y' = max y1 y2 - min y1 y2 + 1
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parse :: String -> [(Int, Int)]
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parse = mapMaybe (fmap fst . uncons . go) . lines
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where
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go :: String -> [(Int, Int)]
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go s = do
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(x, ',' : s1) <- reads s
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(y, []) <- reads s1
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pure (x, y)
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combine :: (Ord a) => [a] -> [(a, a)]
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combine as = S.toList $ foldl' (go as) S.empty as
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where
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go :: (Ord a) => [a] -> Set (a, a) -> a -> Set (a, a)
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go as' pairs b = foldl' (\pairs' a -> if a /= b then S.insert (a, b) pairs' else pairs') pairs as'
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-- | Idea: Generate pairs of all coordinates and calculate the area of
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-- them. Take the maximum.
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part1 :: String -> Int
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part1 = maximum . map (uncurry area) . combine . parse
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part2 :: String -> Int
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part2 = error "Not implemented"
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testInput :: String
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testInput =
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unlines
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[ "7,1",
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"11,1",
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"11,7",
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"9,7",
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"9,5",
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"2,5",
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"2,3",
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"7,3"
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]
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