1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
|
import Control.Monad
import Data.List
import qualified Data.Map.Strict as Map
import Data.Maybe
repSplitAt :: Int -> [a] -> [[a]]
repSplitAt _ [] = []
repSplitAt n l = let (pre, post) = splitAt n l in pre : repSplitAt n post
data Pattern = Pattern Int [Bool]
deriving (Show, Eq, Ord)
parse :: String -> (Pattern, Pattern)
parse str =
let [p1, "=>", p2] = words str
in (parsePat p1, parsePat p2)
parsePat :: String -> Pattern
parsePat str =
let n = length (takeWhile (/= '/') str)
bin = [c == '#' | c <- str, c /= '/']
in Pattern n bin
sp :: Pattern -> String
sp (Pattern n pat) = intercalate "\n" (go pat)
where go [] = []
go p = let (pre, post) = splitAt n p in map ((".#" !!) . fromEnum) pre : go post
genequiv :: Pattern -> [Pattern]
genequiv pat =
let r = take 4 (iterate rotate pat)
in r ++ map mirror r
where
transform f (Pattern n p) = Pattern n [p !! f n x y | y <- [0..n-1], x <- [0..n-1]]
rotate = transform $ \n x y -> n * x + n - 1 - y
mirror = transform $ \n x y -> n * y + (n - 1 - x)
getimg :: Map.Map Pattern Pattern -> Pattern -> Pattern
getimg mp pat = fromJust $ msum $ map (flip Map.lookup mp) (genequiv pat)
adjoin :: [[Bool]] -> [[Bool]] -> [[Bool]]
adjoin a b = map (uncurry (++)) (zip a b)
blocks :: [[Bool]] -> [[[[Bool]]]]
blocks grid =
let n = if length grid `mod` 2 == 0 then 2 else 3
in map transpose $ map (map (repSplitAt n)) $ repSplitAt n grid
pblocks :: [[Bool]] -> [[Pattern]]
pblocks grid =
let n = if length grid `mod` 2 == 0 then 2 else 3
in map (map (Pattern n . concat)) (blocks grid)
unpblocks :: [[Pattern]] -> [[[[Bool]]]]
unpblocks = map $ map $ \(Pattern n p) -> repSplitAt n p
joinblocks :: [[[[Bool]]]] -> [[Bool]]
joinblocks = concatMap (foldl1 adjoin)
main :: IO ()
main = do
mp <- liftM (Map.fromList . map parse . lines) (readFile "21.in")
let orig = [[False, True, False], [False, False, True], [True, True, True]]
iters = iterate (joinblocks . unpblocks . map (map (getimg mp)) . pblocks) orig
-- mapM_ (print . sum . map fromEnum . concat . (iters !!)) [0..]
print (sum $ map fromEnum $ concat $ iters !! 5)
print (sum $ map fromEnum $ concat $ iters !! 18)
|
