49 lines
1.5 KiB
Haskell
49 lines
1.5 KiB
Haskell
|
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
|