AoC2019/day16.hs

import Data.Char

main = do
    cont <- getContents
    let content = drop 5977377 (concat (replicate 10000 (map digitToInt $ init cont) )) 
    let test1 = doStepsP2 content 100 
    putStrLn (show $ length content)
    --mapM putStrLn (map show patter)
    putStrLn (show $ take 8 test1)

getPatternForIndex :: [Int] -> Int -> Int -> [Int]
getPatternForIndex patter length index = drop (1 + index) $ take  (length +1) (cycle base)
                   where base = concat $ map (replicate (index+1)) patter

getInputForIndex :: [Int] -> Int -> [Int]
getInputForIndex xs index = drop index xs 

get :: [Int] -> Int
get xs = mod (abs $ (sum xs)) 10

step :: [Int] -> [[Int]] -> [Int]
step xs patterns = map (\(a,b) -> get( zipWith (*) a b)) $ zip inputs patterns
        where inputs = map (getInputForIndex xs) [0..(length patterns)]

doSteps :: [Int] -> [[Int]] -> Int -> [Int]
doSteps xs patterns cnt 
        | cnt == 0 = xs
        | otherwise = doSteps (step xs patterns) patterns (cnt -1)


stepP2 :: [Int] -> Int -> [Int] -> [Int]
stepP2 xs sumIn acc
        | sumIn == 0 = reverse acc   
        | sumIn > 0 = stepP2 (drop 1 xs) (sumIn - (head xs))  ((mod sumIn 10):acc) 

doStepsP2 :: [Int] -> Int ->[Int]
doStepsP2 xs cnt 
        | cnt == 0 = xs
        | otherwise = doStepsP2 (stepP2 xs (sum(xs)) []) (cnt -1)