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Day 10 - condensed a lot of functions and used normal lists instead of Seq

This commit is contained in:
Jonathan Chan 2017-12-10 11:00:11 -08:00
parent a96ab19024
commit a44830ae8d
1 changed files with 14 additions and 38 deletions
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10.hs
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@ -1,54 +1,30 @@
import Data.List.Split (splitOn) import Data.List.Split (splitOn, chunksOf)
import Data.Sequence (Seq, update, fromList)
import qualified Data.Sequence as S (lookup)
import Data.Char (ord) import Data.Char (ord)
import Data.Bits (xor) import Data.Bits (xor)
import Data.Foldable (toList) import Text.Printf (printf)
import Numeric (showHex)
type Ring = Seq Int
type Position = Int
type Skip = Int
type Length = Int type Length = Int
type State = (Ring, Position, Skip) type State = ([Int], Int, Int)
(%) = mod (%) = mod
unsafeLookup :: Int -> Seq Int -> Int
unsafeLookup index seq =
case S.lookup index seq of
Just i -> i
twist :: State -> Length -> State twist :: State -> Length -> State
twist (ring, position, skip) len = twist (ring, position, skip) len =
let end = position + len - 1 let rotated = slice position 256 $ cycle ring
positions = map (% 256) [position..end] twisted = (reverse $ take len rotated) ++ drop len rotated
posRev = zip positions $ reverse positions newRing = slice (256 - position) 256 $ cycle twisted
newRing = foldl (\currRing (pos, rev) -> update pos (unsafeLookup rev ring) currRing) ring posRev in (newRing, (position + len + skip) % 256, skip + 1)
in (newRing, (end + skip + 1) % 256, skip + 1) where slice start amount = take amount . drop start
hash :: [Length] -> State -> State hash :: [Length] -> State -> State
hash lengths state = foldl twist state lengths hash lengths state = foldl twist state lengths
condense :: [Int] -> [Int]
condense [] = []
condense ns =
let block = foldr xor 0 $ take 16 ns
in block : (condense $ drop 16 ns)
showHexPrepended :: Int -> (String -> String)
showHexPrepended n
| n < 15 = showHex 0 . showHex n
| otherwise = showHex n
main :: IO () main :: IO ()
main = do main = do
input <- readFile "10.txt" input <- readFile "10.txt"
let lengths = map read $ splitOn "," input let lengths = map read $ splitOn "," input
newLengths = map ord input ++ [17, 31, 73, 47, 23] newLengths = map ord input ++ [17, 31, 73, 47, 23]
(hashed, _, _) = hash lengths (fromList [0..255], 0, 0) (hashed, _, _) = hash lengths ([0..255], 0, 0)
(sparseHash, _, _) = iterate (hash newLengths) (fromList [0..255], 0, 0) !! 64 (sparseHash, _, _) = iterate (hash newLengths) ([0..255], 0, 0) !! 64
condensedHash = condense $ toList sparseHash hexString = concat . map (printf "%02x" . foldr xor 0) . chunksOf 16 $ sparseHash :: String
hexString = foldr (\digit str -> showHexPrepended digit $ str) "" condensedHash print $ hashed !! 0 * hashed !! 1
print $ (unsafeLookup 0 hashed) * (unsafeLookup 1 hashed) print $ hexString
print $ hexString