11module AOC2017.Day25 (day25a , day25b ) where
22
3- import AOC2017.Types (Challenge )
3+ import AOC2017.Types (Challenge )
44import AOC2017.Util
5- import AOC2017.Util.Tape
65import Control.Lens
7- import Control.Monad.Trans.Maybe
8- import Control.Monad.Trans.State
9- import Control.Monad.Trans.Writer
10- import Data.Foldable
11- import qualified Data.IntMap as IM
12- import qualified Data.IntSet as IS
13- import qualified Data.Map as M
14- import qualified Data.Set as S
15- import qualified Text.Megaparsec as P
16- import qualified Text.Megaparsec.Char as P
6+ import qualified Data.IntSet as IS
177
188data St = SA | SB | SC | SD | SE | SF
199
2010data Dir = DL | DR
2111
2212type Rule = (Bool Dir , St )
2313
24- type TapeState = (Tape Bool St )
25- 14+ type TapeState = (Int IS. IntSetSt )
2615
2716rule :: St -> (Rule , Rule )
2817rule = \ case
@@ -34,19 +23,21 @@ rule = \case
3423 SF -> ((True DR , SA ), (False DL , SE ))
3524
3625step :: TapeState -> TapeState
37- step (! t0, ! st0) = (t1, st1)
26+ step (! i0, ! t0, ! st0) = (i1, t1, st1)
3827 where
39- t1 = t0 & tFocus .~ newFoc
40- & case dirTurn of
41- DL -> moveLeftD False
42- DR -> moveRightD False
28+ i1 = case dirTurn of
29+ DL -> i0 - 1
30+ DR -> i0 + 1
31+ t1 = t0 & if newFoc
32+ then IS. insert i0
33+ else IS. delete i0
4334 (newFoc, dirTurn, st1)
44- | t0 ^. tFocus = snd (rule st0)
45- | otherwise = fst (rule st0)
35+ | i0 `IS.member` t0 = snd (rule st0)
36+ | otherwise = fst (rule st0)
4637
4738day25a :: Challenge
48- day25a _ = show . length . filter id . toList . fst
49- $ iterate step (Tape [] False [] , SA ) !!! 12964419
39+ day25a _ = show . IS. size . view _2
40+ $ iterate step (0 , IS. empty , SA ) !!! 12964419
5041
5142day25b :: Challenge
52- day25b = undefined
43+ day25b _ = " Merry Christmas! "
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