60 lines
1.9 KiB
Haskell
60 lines
1.9 KiB
Haskell
{-# LANGUAGE TupleSections #-}
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module Day5_1 where
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import System.IO (openFile, IOMode (ReadMode), hClose, hGetContents)
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import Data.Text (splitOn, unpack, pack)
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import Prelude hiding (splitAt)
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import Data.List (sort, intersect)
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import Data.Bifunctor (bimap)
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type Coordinate = (Int, Int)
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type Range = ([Int], [Int])
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toCoord :: String -> Coordinate
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toCoord str = (x, y)
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where
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xy = splitAt "," str
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x = read $ head xy
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y = read $ xy !! 1
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isStraight :: Coordinate -> Coordinate -> Bool
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isStraight c1 c2 = fst c1 == fst c2 || snd c1 == snd c2
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splitAt :: String -> String -> [String]
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splitAt delimiter str = map unpack $ splitOn (pack delimiter) $ pack str
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range :: (Num a, Enum a, Eq a) => a -> a -> [a]
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range a b
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| a == b = [a]
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| otherwise = [a, a + signum (b - a) .. b]
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coordsToRange :: (Coordinate, Coordinate) -> Range
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coordsToRange (a, b) = bimap (range (fst a)) (range (snd a)) b
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points :: (Range, Bool) -> [Coordinate]
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points (range, diag)
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| diag = uncurry zip range
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| otherwise = [ (i,j) | i <- fst range, j <- snd range ]
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intersections :: [(Range, Bool)] -> [[Coordinate]]
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intersections [] = []
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intersections (x:xs) = map (\y -> points x `intersect` points y) xs ++ intersections xs
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dedup :: Eq a => [(a, a)] -> [(a, a)]
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dedup [] = []
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dedup (x:xs) = x : dedup (filter (x /=) xs)
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main :: IO ()
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main = do
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input <- openFile "inputs/5.txt" ReadMode
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contents <- hGetContents input
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let coords = map toCoord . splitAt " -> " <$> lines contents
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-- remove lines that aren't horizontal/vertical and sort them
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let straight' = map sort $ filter (\(x:y:_) -> isStraight x y) coords
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let gay' = filter (\(x:y:_) -> not $ isStraight x y) coords
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let straight = map ((, False) . coordsToRange . (\x -> (head x, x !! 1))) straight'
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let gay = map ((, True) . coordsToRange . (\x -> (head x, x !! 1))) gay'
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print . length . dedup . concat $ intersections $ straight ++ gay
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hClose input |