AoC/2021/day05/day05.hs
2021-12-12 00:49:19 +01:00

28 lines
951 B
Haskell

import qualified Data.Map as M
import Data.List.Split
main :: IO ()
main = do
input <- map (map read . filter (/="->")) <$> map (splitOneOf ", ") <$> lines <$> readFile "input"
let part1inp = filterOrth input
print $ length $ M.filter (> 1) $ M.fromListWith (+) (toMap part1inp)
print $ length $ M.filter (> 1) $ M.fromListWith (+) (toMap input)
filterOrth :: [[Int]] -> [[Int]]
filterOrth [] = []
filterOrth ([x1,y1,x2,y2]:ss)
| x1==x2 || y1==y2 = [x1,y1,x2,y2]:filterOrth ss
| otherwise = filterOrth ss
toMap :: [[Int]] -> [((Int,Int),Int)]
toMap [] = []
toMap ([x1,y1,x2,y2]:xs)
| y1==y2 = zip ySame (repeat 1) ++ toMap xs
| x1==x2 = zip xSame (repeat 1) ++ toMap xs
| otherwise = zip diag (repeat 1) ++ toMap xs
where diag = zip xRange yRange
ySame = zip xRange (repeat y1)
xSame = zip (repeat x1) yRange
xRange = [x1,x1-(signum $ x1-x2)..x2]
yRange = [y1,y1-(signum $ y1-y2)..y2]