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{-# LANGUAGE BangPatterns #-}
import Control.Monad
import Data.Char
import qualified Data.Map.Strict as Map
import Data.Map.Strict ((!))
import Debug.Trace
data Ref = Reg Int | Const Int
deriving Show
data Ins = Set Int Ref | Sub Int Ref | Mul Int Ref | Jnz Ref Ref
deriving Show
parse :: String -> Ins
parse str = case words str of
["set", x, y] -> Set (preg x) (pref y)
["sub", x, y] -> Sub (preg x) (pref y)
["mul", x, y] -> Mul (preg x) (pref y)
["jnz", x, y] -> Jnz (pref x) (pref y)
where
pref s = if isAlpha (head s) then Reg (preg s) else Const (read s)
preg [c] = ord c - ord 'a'
run :: [Ins] -> Int
run program = go 0 0 (Map.fromList [(i, 0) | i <- [0..7]])
where
proglen :: Int
proglen = length program
go :: Int -> Int -> Map.Map Int Int -> Int
go !idx !count _ | idx < 0 || idx >= proglen = count
go !idx !count !regs = case program !! idx of
Set reg ref -> go (succ idx) count (Map.insert reg (getref ref regs) regs)
Sub reg ref -> go (succ idx) count (Map.insert reg (regs ! reg - getref ref regs) regs)
Mul reg ref -> go (succ idx) (succ count) (Map.insert reg (regs ! reg * getref ref regs) regs)
Jnz (Const 0) ref -> go (succ idx) count regs
Jnz (Const _) ref -> go (idx + getref ref regs) count regs
Jnz (Reg r) ref -> go (idx + if regs ! r == 0 then 1 else getref ref regs) count regs
getref :: Ref -> Map.Map Int Int -> Int
getref (Const i) _ = i
getref (Reg r) regs = regs ! r
isprime :: Int -> Bool
isprime n =
let s = floor (sqrt (fromIntegral n))
in not . null $ filter (\d -> n `rem` d == 0) [2..s]
main :: IO ()
main = do
program <- liftM (map parse . lines) (readFile "23.in")
print $ run program
print $ sum $ map (fromEnum . isprime) [106700, 106717 .. 123700]
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