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module Main where
import qualified Data.Map as M
import Control.Monad.Tardis
import qualified Data.ByteString.Char8 as B
import Data.Maybe
import Data.Monoid
type Monkeys = M.Map B.ByteString Int
runMonkeys :: [B.ByteString] -> Tardis Monkeys Monkeys Int
runMonkeys [] = getPast >>= return . fromJust . M.lookup (B.pack "root")
runMonkeys (x:xs) = case number of
Just (number, _) -> do
modifyBackwards (M.insert name number)
modifyForwards (M.insert name number)
runMonkeys xs
Nothing -> do
bw <- getFuture
fw <- getPast
-- union is REALLY slow
let lookup k = First (M.lookup k bw) <> First (M.lookup k fw)
let v = case lookup lhs of
First (Just lhs') -> case lookup rhs of
First (Just rhs') -> fn lhs' rhs'
modifyBackwards (M.insert name v)
modifyForwards (M.insert name v)
runMonkeys xs
where
name = B.take 4 x
-- readMaybe is slowwww
number = B.readInt (B.drop 6 x)
expression = fromJust $ x B.!? 11
fn = case expression of
'+' -> (+)
'*' -> (*)
'/' -> div
'-' -> (-)
lhs = B.take 4 $ B.drop 6 x
rhs = B.take 4 $ B.drop 13 x
main = B.readFile "input.txt" >>= (print . (`evalTardis` (M.empty, M.empty)) . runMonkeys . B.lines)
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