diff options
| -rw-r--r-- | 2019/3.hs | 15 |
1 files changed, 15 insertions, 0 deletions
@@ -2,6 +2,7 @@ module Main where import Data.Char import Data.List +import qualified Data.Map.Strict as Map import qualified Data.Set as Set import Input @@ -48,8 +49,22 @@ points (Seg pt dir n) = manhattan :: Pt -> Int manhattan (Pt x y) = abs x + abs y +data Hit = Hit {hitPt :: Pt, hitIdx :: Int} deriving (Show) +instance Eq Hit where Hit p _ == Hit q _ = p == q +instance Ord Hit where compare (Hit p _) (Hit q _) = compare p q + +points2 :: Int -> [Seg] -> [Hit] +points2 _ [] = [] +points2 start (Seg pt dir n : segs) = + let delta = direction dir + in [Hit (add pt (scale k delta)) (start + k) | k <- [1..n]] ++ points2 (start + n) segs + main :: IO () main = do ls <- map (process (Pt 0 0) . parse) <$> getInput 3 let pts = Set.toList (foldl1 Set.intersection (map (Set.fromList . concatMap points) ls)) print (manhattan (head (sortOn manhattan pts))) + + let idxMap1 = Map.fromList . reverse $ [(hitPt h, hitIdx h) | h <- points2 0 (ls !! 0)] + idxMap2 = Map.fromList . reverse $ [(hitPt h, hitIdx h) | h <- points2 0 (ls !! 1)] + print $ minimum (zipWith (+) (map (idxMap1 Map.!) pts) (map (idxMap2 Map.!) pts)) |