X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=src%2Fadvent14%2Fadvent14serial.hs;fp=src%2Fadvent14%2Fadvent14serial.hs;h=3e4ef209c00307d9dc18d139dd9ed1083f64d93f;hb=37cd040f05eb3882ae06d198fab729373f7d8c92;hp=0000000000000000000000000000000000000000;hpb=8685ec38046f10f7bb38a58dcb791d35d35796e8;p=advent-of-code-17.git

diff --git a/src/advent14/advent14serial.hs b/src/advent14/advent14serial.hs
new file mode 100644
index 0000000..3e4ef20
--- /dev/null
+++ b/src/advent14/advent14serial.hs
@@ -0,0 +1,96 @@
+import Data.List.Split (chunksOf)
+import Data.Char (ord)
+import Text.Printf (printf)
+import Data.Bits (xor)
+import qualified Data.Map.Strict as M
+import qualified Data.Graph as G
+-- import Control.Parallel.Strategies (parMap, rpar)
+type CellMap = M.Map (Int, Int) Bool
+
+puzzleKey = "xlqgujun"
+
+main :: IO ()
+main = do
+  print $ part1 puzzleKey
+  print $ part2 puzzleKey
+
+
+part1 :: String -> Int
+part1 key = sum rowCounts
+    where rowCounts = map countSetBits $ binHashes key
+
+
+part2 :: String -> Int
+part2 key = length $ cellEdges cells
+    where cells = presentCells $ binHashes key
+
+binHashes :: String -> [String]
+binHashes key = map binHash $ rowSpecs key
+
+
+binHash :: String -> String
+binHash = binify . knotHash
+
+numKey :: (Int, Int) -> Int
+numKey (r, c) = 128 * r + c
+
+
+presentCells :: [String] -> CellMap
+presentCells bhs = M.fromList [((r, c), True) | r <- [0..127], c <- [0..127], (bhs!!r)!!c == '1']
+
+adjacentCells :: CellMap -> (Int, Int) -> [(Int, Int)]
+adjacentCells cells (r, c) = filter (\k -> M.member k cells) possibles
+  where possibles = [(r, c - 1), (r, c + 1), (r - 1, c), (r + 1, c)]
+
+
+cellEdges :: CellMap -> [G.SCC (Int, Int)]
+cellEdges cells = G.stronglyConnComp [(k, numKey k, map numKey $ adjacentCells cells k) | k <- M.keys cells]
+
+rowSpecs :: String -> [String]
+rowSpecs key = map (((key ++ "-") ++) . show) ([0..127] :: [Integer])
+
+countSetBits :: String -> Int
+countSetBits = length . filter (== '1')
+
+
+
+knotHash :: String -> [Int]
+knotHash input = densify tied
+    where (tied, _, _) = foldl step ([0..255], 0, 0) hashTerms
+          hashTerms = mkHashTerms input
+
+step :: ([Int], Int, Int) -> Int -> ([Int], Int, Int)
+step (original, start, skip) len = (replaced, start', skip + 1)
+    where replaced = tie original start len
+          start' = (start + len + skip) `mod` (length original)
+
+tie :: [a] -> Int -> Int -> [a]
+tie original start len = replace original replacement start
+    where replacement = reverse $ extract original start len
+
+extract :: [a] -> Int -> Int -> [a]
+extract items from len = take len $ drop from $ items ++ items
+
+replace :: [a] -> [a] -> Int -> [a]
+replace original replacement from = take (length original) (start ++ replacement ++ remainder)
+    where excess = drop (length original - from) replacement
+          stub = drop (length excess) original
+          start = take from (excess ++ stub)
+          remainder = drop (length $ start ++ replacement) original 
+
+
+mkHashTerms :: String -> [Int]
+mkHashTerms text = take (length chunk * 64) $ cycle chunk
+    where chunk = map ord text ++ [17, 31, 73, 47, 23]
+
+-- hexify :: [Int] -> String
+-- hexify = concatMap (printf "%02x")
+
+binify :: [Int] -> String
+binify = concatMap (printf "%08b")
+
+densify :: [Int] -> [Int]
+densify ns = codes
+    where chunks = chunksOf 16 ns
+          compress = foldl1 xor
+          codes = map compress chunks