AoC/2021/day08/day08.hs

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2021-12-18 20:27:37 +01:00
import Data.List.Split
import Data.List
import qualified Data.Map.Strict as M
main :: IO ()
main = do
input <- map (map (map sort . words) . splitOn "|") <$> lines <$> readFile "day08/input"
let output = map (!!1) input
print $ length $ filter (`elem` [2,3,4,7]) $ map length (concat output)
print $ day08 input
-- string auf int hashmap machen?
findDict :: [String] -> M.Map Char Char
findDict wire = M.fromList $ zip (a++b++c++d++e++f++g) "abcdefg"
where a = intersect (getX 3) (without [2,4]) --done
b = intersect (charsWithLength 3 6) (charsWithLength 1 5) --done?
c = intersect (charsWithLength 2 6) (getX 2) --done?
d = intersect (charsWithLength 2 6) (charsWithLength 3 5) --done?
e = intersect (charsWithLength 1 5) $ intersect (getX 7) $ without [2..4] --done?
f = getX 2 \\ c --done
g = without [2..4] \\ e --done?
without x = "abcdefg" \\ (concat $ filter (flip elem x . length) wire)
getXs x = filter (\y->length y == x) wire
getX = head . getXs
charsWithLength x c = nub $ concat $ filter (\y->length y == x) $ group $ sort $ concat $ getXs c
decode :: M.Map Char Char -> String -> String
decode _ [] = []
decode dict (x:xs) = dict M.! x : decode dict xs
findNum :: String -> Int
findNum x
| x=="abcefg" = 0
| x=="cf" = 1
| x=="acdeg" = 2
| x=="acdfg" = 3
| x=="bcdf" = 4
| x=="abdfg" = 5
| x=="abdefg" = 6
| x=="acf" = 7
| x=="abcdefg" = 8
| x=="abcdfg" = 9
day08 :: [[[String]]] -> Int
day08 [] = 0
day08 ((wire:output):xs) = day08 xs + (sum $ zipWith (*) decoded [10^x|x<-[0..]])
where dict = findDict wire
decoded = reverse $ map (findNum . sort . decode dict) (head output)