Day 13: started, but have meetings

advent-of-code.cabal

@@ -10,7 +10,7 @@ maintainer:         stuart@cs.uchicago.edu
 common aoc-common
   build-depends       : base ^>=4.14.3.0, array, containers
   hs-source-dirs      : src
-  other-extensions    : TypeApplications
+  default-extensions  : TypeApplications
   default-language    : Haskell2010
   ghc-options         : -Wall
  

src/AOC-12a.hs

-{-# LANGUAGE TypeApplications #-}
-
 module Main where
 
 import Control.Monad ( void, guard )
@@ -7,7 +5,6 @@ import Data.Char ( isUpper, isAlpha )
 import qualified Data.Map as M
 import Data.Map (Map,(!))
 import qualified Data.Set as S
-import Data.Set (Set)
 import Text.ParserCombinators.ReadP
     ( char, munch1, readP_to_S, ReadP )
 
@@ -42,7 +39,6 @@ makeCaveMap es =
 
 paths :: CaveMap -> [[Cave]]
 paths cm = iter (Small "start") (S.singleton (Small "start")) [Small "start"] where
-  iter :: Cave -> Set Cave -> [Cave] -> [[Cave]]
   iter (Small "end") _ path = [reverse path]
   iter cave visited path = do
     next <- cm ! cave

src/AOC-12b.hs

-{-# LANGUAGE TypeApplications #-}
-
 module Main where
 
 import Control.Monad ( guard, void )
@@ -7,7 +5,6 @@ import Data.Char ( isUpper, isAlpha )
 import qualified Data.Map as M
 import Data.Map (Map,(!))
 import qualified Data.Set as S
-import Data.Set (Set)
 import Text.ParserCombinators.ReadP
     ( char, munch1, readP_to_S, ReadP )
 
@@ -26,8 +23,7 @@ type CaveMap = Map Cave [Cave]
 parseCave :: ReadP Cave
 parseCave = do
   nm <- munch1 isAlpha
-  pure $
-    if isUpper (head nm) then Big nm else Small nm
+  pure $ if isUpper (head nm) then Big nm else Small nm
 
 parseEdge :: ReadP Edge
 parseEdge = do
@@ -41,12 +37,12 @@ makeCaveMap es =
   M.unionsWith (++) . map (\(Edge c1 c2) -> M.fromList [(c1,[c2]),(c2,[c1])]) $ es
 
 paths :: CaveMap -> [[Cave]]
-paths cm = iter (Small "start") (S.singleton (Small "start")) False [Small "start"] where
-  iter :: Cave -> Set Cave -> Bool -> [Cave] -> [[Cave]]
+paths cm = iter start (S.singleton start) False [start] where
+  start = Small "start"
   iter (Small "end") _ _ path = [reverse path] -- end at end
   iter cave visited revisited path = do
     next <- cm ! cave
-    guard $ next /= Small "start" -- don't revist start
+    guard $ next /= start -- don't revist start
     if next `elem` visited
     then do
       guard $ not revisited

src/AOC-13a.hs

 module Main where
 
+import Data.Array
+import Data.Char
+import Data.Functor
+import Text.ParserCombinators.ReadP
+
+data Fold
+  = FoldX Int
+  | FoldY Int
+  deriving Show
+
+data Instructions = Instructions
+  { dots :: [(Int,Int)]
+  , folds :: [Fold]
+  } deriving Show
+
+parseInt :: ReadP Int
+parseInt = read <$> munch1 isDigit
+
+parseFold :: ReadP Fold
+parseFold = parseDirection <*> parseInt where
+  parseDirection = parseFold' 'x' FoldX <++ parseFold' 'y' FoldY
+  parseFold' c op = string "fold along " *> char c *> char '=' $> op
+
+parseInstructions :: ReadP Instructions
+parseInstructions = do
+  ds <- many $ do
+    x <- parseInt
+    void $ char ','
+    y <- parseInt
+    skipSpaces
+    pure $ (x,y)
+  fs <- many $ parseFold <* skipSpaces
+  pure $ Instructions ds fs
+
+instance Read Instructions where
+  readsPrec _ = readP_to_S parseInstructions
+
+data Pixels = Pixels { getPixels :: Array (Int,Int) Bool }
+
+makePixels :: [(Int,Int)] -> Pixels
+makePixels ps = Pixels $ accumArray (\_ _ -> True) False  ((0,0),(xMax,yMax)) mps where
+  xMax = maximum $ map fst ps
+  yMax = maximum $ map snd ps
+  mps = [(p,()) | p <- ps]
+
+showPixels :: Pixels -> String
+showPixels (Pixels parr) = unlines scanLines where
+  scanLines = [ [ toPixel $ parr ! (x,y) | x <- [0..xMax] ] | y <- [0..yMax] ]
+  ((0,0),(xMax,yMax)) = bounds parr
+  toPixel True = '#'
+  toPixel False = '.'
+
 main :: IO ()
-main = pure ()
+main = do
+  input <- read @Instructions <$> readFile "test/dots.txt"
+  putStr . showPixels . makePixels . dots $ input

test/dots.txt

+6,10
+0,14
+9,10
+0,3
+10,4
+4,11
+6,0
+6,12
+4,1
+0,13
+10,12
+3,4
+3,0
+8,4
+1,10
+2,14
+8,10
+9,0
+
+fold along y=7
+fold along x=5
\ No newline at end of file