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import Data.List (find, transpose)
import qualified Data.Set as Set
import qualified Data.Text as Text
import qualified Data.Text.IO as Text
countVisibleTrees ::
[[Int]] -> [Int] -> Int -> (Set.Set (Int, Int)) -> (Set.Set (Int, Int))
countVisibleTrees [] _ _ seen = seen
countVisibleTrees (row:rows) maxTrees depth seen =
countVisibleTrees
rows
(zipWith (\x y -> max x y) row maxTrees)
(depth + 1)
(foldl
(\acc x -> Set.insert x acc)
seen
(zipWith
(\i x ->
if x == 1
then (depth, i)
else (0, 0))
[0 ..]
(zipWith
(\x y ->
if x > y
then 1
else 0)
row
maxTrees)))
treeScore :: [[Int]] -> (Int, Int) -> Int -> Int -> [Int]
treeScore digits (x, y) width height =
let currentHeight = ((digits !! y) !! x)
in [ (case (find
(\x -> (digits !! y) !! x >= currentHeight)
[(x + 1) .. (width - 1)]) of
Just value -> (value - x)
Nothing -> (width - x - 1))
, (case (find
(\x -> (digits !! y) !! x >= currentHeight)
(reverse [0 .. (x - 1)])) of
Just value -> (x - value)
Nothing -> x)
, (case (find
(\y -> (digits !! y) !! x >= currentHeight)
(reverse [0 .. (y - 1)])) of
Just value -> (y - value)
Nothing -> y)
, (case (find
(\y -> (digits !! y) !! x >= currentHeight)
[(y + 1) .. (height - 1)]) of
Just value -> (value - y)
Nothing -> (height - y - 1))
]
getDigitsFromString :: String -> [Int]
getDigitsFromString = map (read . (: ""))
rotl :: [[Int]] -> [[Int]]
rotl = reverse . transpose
rotr :: [[Int]] -> [[Int]]
rotr = transpose . reverse
mmult :: [[Int]] -> [[Int]] -> [[Int]]
mmult a b = [[sum $ zipWith (*) ar bc | bc <- (transpose b)] | ar <- a]
main = do
ls <- fmap Text.lines (Text.readFile "input")
let digits = map (getDigitsFromString . Text.unpack) ls
let height = length digits
let width = length (head digits)
let topDownSeen =
countVisibleTrees digits (take width (repeat (-1))) 0 Set.empty
let rightLeftSeen =
Set.map
(\x -> ((snd x), width - (fst x) - 1))
(countVisibleTrees
(rotl digits)
(take height (repeat (-1)))
0
Set.empty)
let downTopSeen =
Set.map
(\x -> (height - (fst x) - 1, (snd x)))
(countVisibleTrees
(reverse digits)
(take width (repeat (-1)))
0
Set.empty)
let leftRightSeen =
Set.map
(\x -> (height - (snd x) - 1, (fst x)))
(countVisibleTrees
(rotr digits)
(take height (repeat (-1)))
0
Set.empty)
let allSeen =
(foldl
(\acc x -> Set.union acc x)
Set.empty
[topDownSeen, rightLeftSeen, downTopSeen, leftRightSeen])
print (Set.size allSeen)
print
(maximum
(map
(\y ->
maximum
(map
(\x ->
(foldl
(\acc x -> acc * x)
1
(treeScore digits (x, y) width height)))
[0 .. (width - 1)]))
[0 .. (height - 1)]))
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