Day 14 part 1

[advent-of-code-20.git] / advent14 / src / advent14.hs

diff --git a/advent14/src/advent14.hs b/advent14/src/advent14.hs
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+-- import Debug.Trace
+
+import Data.Text (Text)
+-- import qualified Data.Text as T
+import qualified Data.Text.IO as TIO
+
+import Data.Attoparsec.Text hiding (take)
+-- import Data.Attoparsec.Combinator
+import Control.Applicative
+
+import Data.Int
+import Data.Bits
+import Data.Char
+import Data.List
+
+import qualified Data.Map.Strict as M
+import Data.Map.Strict ((!))
+
+
+type MaskMap = M.Map Int Int
+data Instruction = Mask MaskMap | Assignment Int64 Int64
+  deriving (Show, Eq)
+
+type Memory = M.Map Int64 Int64
+data Machine = Machine { mMemory :: Memory
+                       , mMask0 :: Int64
+                       , mMask1 :: Int64
+                       } deriving (Show, Eq)
+
+emtpyMachine = Machine M.empty (complement 0) 0
+
+
+main :: IO ()
+main = 
+  do  text <- TIO.readFile "data/advent14.txt"
+      let program = successfulParse text
+      print $ take 6 program
+      print $ part1 program
+
+
+part1 program = sum $ M.elems $ mMemory finalMachine
+  where finalMachine = executeInstructions program
+
+executeInstructions instructions = 
+  foldl' executeInstruction emtpyMachine instructions
+
+executeInstruction machine (Mask mask) = makeMask machine mask
+executeInstruction machine (Assignment loc value) = assignValue machine loc value
+
+
+makeMask machine mask = 
+  machine {mMask0 = maskZeroes mask, mMask1 = maskOnes mask}
+
+maskValue machine value = 
+  (value .|. (mMask1 machine)) .&. (mMask0 machine)
+
+assignValue machine loc value = 
+  machine {mMemory = M.insert loc value' mem}
+  where value' = maskValue machine value
+        mem = mMemory machine
+
+
+maskOnes :: MaskMap -> Int64
+maskOnes mask = foldl' setBit zeroBits ones
+  where ones = M.keys $ M.filter (== 1) mask
+
+maskZeroes :: MaskMap -> Int64
+maskZeroes mask = complement $ foldl' setBit zeroBits ones
+  where ones = M.keys $ M.filter (== 0) mask
+
+
+-- Parse the input file
+
+programP = (maskP <|> assignmentP) `sepBy` endOfLine
+
+maskP = maskify <$> ("mask = " *> (many (digit <|> letter)))
+assignmentP = Assignment <$> ("mem[" *> decimal) <* "] = " <*> decimal
+
+maskify :: String -> Instruction
+maskify chars = Mask (M.fromList locNums)
+  where locChars = zip [0..] $ reverse chars
+        locDigits = filter (isDigit . snd) locChars
+        locNums = map (\(i, n) -> (i, read @Int [n])) locDigits
+
+
+-- successfulParse :: Text -> (Integer, [Maybe Integer])
+successfulParse input = 
+  case parseOnly programP input of
+    Left  _err -> [] -- TIO.putStr $ T.pack $ parseErrorPretty err
+    Right program -> program