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Day 14, part 2 - partial progress

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Jonathan Chan 2017-12-13 23:30:42 -08:00
parent 3ca34256b1
commit ac2c786b6c
1 changed files with 12 additions and 0 deletions
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14.hs
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@ -2,6 +2,8 @@ import Data.List.Split (chunksOf)
import Data.Char (ord)
import Data.Bits (xor)
import Text.Printf (printf)
import Data.Matrix (Matrix, fromLists, safeGet)
import Data.HashSet (Set, member, insert)
type Length = Int
type State = ([Int], Int, Int)
@ -23,9 +25,19 @@ sparseHash lengths =
let (hashed, _, _) = iterate (hash lengths) ([0..255], 0, 0) !! 64
in concat . map (printf "%08b" . foldr xor 0) . chunksOf 16 $ hashed
visit :: Matrix Int -> (Int, Int) -> Set (Int, Int) -> Set (Int, Int)
visit matrix (row, col) seen = if member (row, col) seen then seen else
let newSeen = insert (row, col) seen
in
case safeGet row col matrix of
Nothing -> seen
Just 0 -> newSeen
Just 1 -> foldr (visit matrix) newSeen [(row + 1, col), (row - 1, col), (row, col + 1), (row, col - 1)]
main :: IO ()
main = do
let hashes = map (sparseHash . (++ [17, 31, 73, 47, 23]) . map ord . ("ffayrhll-" ++) . show) [0..127]
used = length . filter (== '1') . concat $ hashes
matrix = fromLists hashes
print $ used
mapM_ print hashes