import Data.Char
import Data.List
import Data.Array

main :: IO ()
main = do
  input <- readFile "input"
  let grid = makeGrid (lines input)
  print $ part1 grid
  print $ part2 grid

part1 grid =
  let heads = filter (\p -> grid!p == 0) (indices grid)
  in sum $ map (getScore grid) heads

part2 grid =
  let heads = filter (\p -> grid!p == 0) (indices grid)
  in sum $ map (getRating grid) heads

getScore grid pos = length $ nub $ find9s grid 0 pos
getRating grid pos = length $ find9s grid 0 pos

find9s grid 9 pos = if (grid!pos) == 9 then [pos] else []
find9s grid i pos =
  let neigh = getNeighbours grid pos
      next = filter (\p -> (grid!p) == i+1) neigh
  in concatMap (find9s grid (i+1)) next

getNeighbours arr (i,j) = filter (inRange (bounds arr)) [(i-1,j),(i+1,j),(i,j-1),(i,j+1)]

makeGrid :: [String] -> Array (Int, Int) Int
makeGrid grid = array bounds elements
  where n = length grid
        m = length (head grid)
        bounds = ((0,0), (n-1,m-1))
        elements = [((i,j), digitToInt (grid!!i!!j)) |
                    i <- [0..n-1], j <- [0..m-1]]