diff options
| -rw-r--r-- | 2024/.gitignore | 6 | ||||
| -rw-r--r-- | 2024/10.hs | 24 |
2 files changed, 30 insertions, 0 deletions
diff --git a/2024/.gitignore b/2024/.gitignore index 6a16c5a..0dfba9a 100644 --- a/2024/.gitignore +++ b/2024/.gitignore @@ -11,3 +11,9 @@ aoc-cookie.txt 7 8 9 +10 +11 +12 +13 +14 +15 diff --git a/2024/10.hs b/2024/10.hs new file mode 100644 index 0000000..cbb291c --- /dev/null +++ b/2024/10.hs @@ -0,0 +1,24 @@ +import qualified Data.Array as A +import Data.Array (Array, (!)) +import Data.Foldable (toList) +import qualified Data.Set as Set +import Data.Bifunctor (bimap) + +amap :: A.Ix i => (i -> a -> b) -> Array i a -> Array i b +amap f arr = A.listArray (A.bounds arr) (zipWith f (A.indices arr) (toList arr)) + +main :: IO () +main = do + topo' <- map (map (read @Int . pure)) . lines <$> getContents + let w = length (head topo') + let h = length topo' + let topo = A.listArray ((0, 0), (w - 1, h - 1)) (concat topo') + let flood9 = amap (\i n -> if n == 9 then (Set.singleton i, 1::Int) else (mempty, 0)) topo + let inBounds (x, y) = 0 <= x && x < w && 0 <= y && y < h + let neighs (x, y) = filter inBounds [(x-1,y), (x+1,y), (x,y-1), (x,y+1)] + let stepdown mp = + amap (\i n -> bimap Set.unions sum $ unzip [mp ! p | p <- neighs i, topo ! p == n + 1]) topo + let flood = iterate stepdown flood9 !! 9 + let (totscore, totrank) = bimap sum sum $ unzip $ map (\((s,n),_) -> (Set.size s, n)) $ filter (\(_,n) -> n == 0) $ zip (A.elems flood) (A.elems topo) + print totscore + print totrank |