module Main where

import Utils
import Data.List (sort)
import Control.Monad
import Control.Monad.Memo

parseLine :: String -> Int
parseLine = read

diffs :: [Int] -> Int
diffs s = product $ ($ q s) <$> [howMany (==1), howMany (==3)]
    where q = zipWith subtract `ap` tail

combos top s = startEvalMemo $ go 0
    where go c
            | c == top = return 1
            | otherwise = do
                let cs = filter (`elem` s) $ map (+c) [1,2,3]
                sum <$> mapM (memo go) cs

main :: IO ()
main = do
    n <- map parseLine . lines <$> readFile "input/10"
    let top = maximum n + 3
        ls = sort (0:top:n)
    print $ diffs ls
    print $ combos top ls