Day 5

Day5.hs

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+module Day5 where
+import System.IO (openFile, IOMode (ReadMode), hClose, hGetContents)
+import Data.Text (splitOn, unpack, pack)
+import Prelude hiding (splitAt)
+import Data.List (sort, intersect)
+
+type Coordinate = (Int, Int)
+type Range = ([Int], [Int])
+
+toCoord :: String -> Coordinate
+toCoord str = (x, y)
+    where
+        xy = splitAt "," str
+        x = read $ head xy
+        y = read $ xy !! 1
+
+isStraight :: Coordinate -> Coordinate -> Bool
+isStraight c1 c2 = fst c1 == fst c2 || snd c1 == snd c2
+
+splitAt :: String -> String -> [String]
+splitAt delimiter str = map unpack $ splitOn (pack delimiter) $ pack str
+
+coordsToRange :: (Coordinate, Coordinate) -> Range
+coordsToRange (a, b) = ([fst a..fst b], [snd a.. snd b])
+
+points :: Range -> [Coordinate]
+points range = [ (i,j) | i <- fst range, j <- snd range ]
+
+intersections :: [Range] -> [[Coordinate]]
+intersections [] = []
+intersections (x:xs) = map (\y -> points x `intersect` points y) xs ++ intersections xs
+
+dedup :: Eq a => [(a, a)] -> [(a, a)]
+dedup [] = []
+dedup (x:xs) = x : dedup (filter (x /=) xs)
+
+main :: IO ()
+main = do
+    input <- openFile "inputs/5.txt" ReadMode
+    contents <- hGetContents input
+
+    let coords = map toCoord . splitAt " -> " <$> lines contents
+    -- remove lines that aren't horizontal/vertical and sort them
+    let lines = map sort $ filter (\x -> isStraight (head x) (x !! 1)) coords
+    let pairs = map (coordsToRange . (\x -> (head x, x !! 1))) lines
+
+    print . length . dedup . concat $ intersections pairs
+
+    hClose input

Day5_1.hs

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