day17

day17/LICENSE

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+Copyright Ilya Bobyr (c) 2019
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Ilya Bobyr nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

day17/README.md

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+# day17

day17/Setup.hs

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+import Distribution.Simple
+main = defaultMain

day17/day17.cabal

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+name:                day17
+version:             0.1.0.0
+-- synopsis:
+-- description:
+homepage:            https://github.com/ilya-bobyr/advent-of-code-2018/day17#readme
+license:             BSD3
+license-file:        LICENSE
+author:              Ilya Bobyr
+maintainer:          [email protected]
+copyright:           (c) 2018 Ilya Bobyr
+category:            Web
+build-type:          Simple
+cabal-version:       >=1.10
+extra-source-files:  README.md
+
+executable day17
+  hs-source-dirs:      src
+  main-is:             Main.hs
+  default-language:    Haskell2010
+  ghc-options:         -O2 -fdiagnostics-color=always
+  build-depends:       base >= 4.7 && < 5
+                     , array
+                     , control-bool
+                     , parsec

day17/src/Main.hs

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+{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE FlexibleContexts #-}
+
+module Main where
+
+import Control.Bool ((<&&>))
+import Control.Monad (foldM, sequence)
+import Control.Monad.ST (ST, runST)
+import Data.Array.MArray (readArray, writeArray)
+import qualified Data.Array.MArray as MA
+import Data.Array (Array)
+import Data.Array.ST (STArray)
+import Data.List (foldl', intercalate)
+import Data.Maybe (catMaybes)
+import System.Environment (getArgs)
+import System.IO (Handle, hGetContents, IOMode(ReadMode), stdin, withFile)
+import Text.Parsec (parse)
+import Text.Parsec.Char (digit, string, newline)
+import Text.Parsec.Combinator (eof, many1, sepEndBy)
+import Text.Parsec.Prim (try, (<|>))
+import Text.Parsec.String (Parser)
+
+-- import Debug.Trace (traceM)
+
+data BoardCell = Sand
+               | Clay
+               | MovingWater
+               | StillWater
+               deriving (Eq)
+
+instance Show BoardCell where
+  show Sand = "."
+  show Clay = "#"
+  show MovingWater = "|"
+  show StillWater = "~"
+
+flowAbove :: BoardCell -> Bool
+flowAbove = \case Clay -> True
+                  StillWater -> True
+                  _ -> False
+
+type Board s = STArray s (Int, Int) BoardCell
+type IBoard = Array (Int, Int) BoardCell
+
+showBoard :: Board s -> ST s String
+showBoard board = do
+  ((minY, minX), (maxY, maxX)) <- MA.getBounds board
+  let asChar = \case Sand -> '.'
+                     Clay -> '#'
+                     MovingWater -> '|'
+                     StillWater -> '~'
+
+  intercalate "\n" <$>
+    sequence [
+        sequence [
+            asChar <$> readArray board (y, x) | x <- [minX..maxX]]
+        | y <- [minY..maxY]]
+
+data InputCommand = Horizontal Int (Int, Int)
+                  | Vertical (Int, Int) Int
+                  deriving (Eq, Show)
+
+horizontalCommandParser :: Parser InputCommand
+horizontalCommandParser = do
+  _ <- string "y="
+  y <- read <$> many1 digit
+  _ <- string ", x="
+  minX <- read <$> many1 digit
+  _ <- string ".."
+  maxX <- read <$> many1 digit
+  return $ Horizontal y (minX, maxX)
+
+verticalCommandParser :: Parser InputCommand
+verticalCommandParser = do
+  _ <- string "x="
+  x <- read <$> many1 digit
+  _ <- string ", y="
+  minY <- read <$> many1 digit
+  _ <- string ".."
+  maxY <- read <$> many1 digit
+  return $ Vertical (minY, maxY) x
+
+commandParser :: Parser InputCommand
+commandParser =
+  try horizontalCommandParser
+  <|> verticalCommandParser
+
+inputParser :: Parser [InputCommand]
+inputParser = do
+  commands <- commandParser `sepEndBy` newline
+  eof
+  return commands
+
+commandBounds :: InputCommand -> ((Int, Int), (Int, Int))
+commandBounds (Horizontal y (minX, maxX)) = ((y, minX), (y, maxX))
+commandBounds (Vertical (minY, maxY) x) = ((minY, x), (maxY, x))
+
+buildBoard :: [InputCommand] -> ST s (Board s)
+buildBoard commands =
+  let buildBounds ((!minY, !minX), (!maxY, !maxX))
+        ((cMinY, cMinX), (cMaxY, cMaxX)) =
+        let minX' = if cMinX < minX then cMinX else minX
+            maxX' = if cMaxX > maxX then cMaxX else maxX
+            minY' = if cMinY < minY then cMinY else minY
+            maxY' = if cMaxY > maxY then cMaxY else maxY
+        in ((minY', minX'), (maxY', maxX'))
+
+      bounds =
+        foldl' buildBounds ((0, 500), (0, 500))
+        $ map commandBounds commands
+
+      extendXBy dx ((!minY, !minX), (!maxY, !maxX)) =
+        ((minY, minX - dx), (maxY, maxX + dx))
+
+      applyCommand :: Board s -> InputCommand -> ST s (Board s)
+      applyCommand board (Horizontal y (minX, maxX)) = do
+        mapM_ (\x -> writeArray board (y, x) Clay) [minX..maxX]
+        return board
+      applyCommand board (Vertical (minY, maxY) x) = do
+        mapM_ (\y -> writeArray board (y, x) Clay) [minY..maxY]
+        return board
+  in do
+    initial <- MA.newArray (extendXBy 1 bounds) Sand
+    foldM applyCommand initial commands
+
+findMinY :: [InputCommand] -> Int
+findMinY commands =
+  let getY c = case commandBounds c of
+        ((minY, _), _) -> minY
+
+      go !mY [] = mY
+      go !mY (c:cs) =
+        let mY' = if mY < getY c then mY else getY c
+        in go mY' cs
+  in go (getY $ head commands) $ tail commands
+
+flowWaterOneTick :: Board s -> [(Int, Int)] -> ST s [(Int, Int)]
+flowWaterOneTick _ [] = return []
+flowWaterOneTick board (p:ps) = do
+  (_, (maxY, _)) <- MA.getBounds board
+  let extendDown (!y, !x) = do
+        belowCell <- readArray board (y+1, x)
+        case belowCell of
+          Sand -> do writeArray board (y+1, x) MovingWater
+                     return [(y+1, x)]
+          Clay -> extendSideways (y, x)
+          MovingWater -> return []
+          StillWater -> extendSideways (y, x)
+
+      boundedOn dir (!y, !x) = do
+        belowCell <- readArray board (y+1, x)
+        if flowAbove belowCell
+          then do dirCell <- readArray board (y, dir x)
+                  case dirCell of
+                    Sand -> boundedOn dir (y, dir x)
+                    Clay -> return True
+                    StillWater -> return True
+                    MovingWater -> boundedOn dir (y, dir x)
+          else return False
+
+      boundedOnBothSides (y, x) =
+        boundedOn (subtract 1) (y, x) <&&> boundedOn (+1) (y, x)
+
+      extendTo dir as (!y, !x) = do
+        belowCell <- readArray board (y+1, x)
+        let fillAndContinue =
+              do writeArray board (y, x) as
+                 dirCell <- readArray board (y, dir x)
+                 case dirCell of
+                    Sand -> extendTo dir as (y, dir x)
+                    Clay -> return Nothing
+                    MovingWater -> extendTo dir as (y, dir x)
+                    StillWater -> return Nothing
+
+            fillAndExtend =
+              do writeArray board (y, x) as
+                 return $ Just (y, x)
+
+        case belowCell of
+          Sand -> fillAndExtend
+          Clay -> fillAndContinue
+          MovingWater -> return Nothing
+          StillWater -> fillAndContinue
+
+      extendSideways (!y, !x) = do
+        isBounded <- boundedOnBothSides (y, x)
+        if isBounded
+          then do _ <- extendTo (subtract 1) StillWater (y, x)
+                  _ <- extendTo (+1) StillWater (y, x)
+                  return [(y-1, x)]
+          else do left <- extendTo (subtract 1) MovingWater (y, x)
+                  right <- extendTo (+1) MovingWater (y, x)
+                  return $ catMaybes [left, right]
+
+  if fst p == maxY
+    then return ps
+    else do -- boardText <- showBoard board
+            -- traceM "---------"
+            -- traceM $ show (p:ps)
+            -- bounds <- MA.getBounds board
+            -- traceM $ show bounds
+            -- traceM boardText
+            ps' <- extendDown p
+            return $ ps' ++ ps
+
+flowWater :: Board s -> [(Int, Int)] -> ST s ()
+flowWater _ [] = return ()
+flowWater board ps = do
+  ps' <- flowWaterOneTick board ps
+  flowWater board ps'
+
+countCells :: Board s -> Int -> (BoardCell -> Bool) -> ST s Int
+countCells board minY target =
+  length
+    . filter target
+    . map snd
+    . filter ((>= minY) . fst . fst)
+    <$> MA.getAssocs board
+
+main :: IO ()
+main = do
+  args <- getArgs
+  case args of
+      [] -> run stdin
+      file:_ ->
+        withFile file ReadMode run
+
+run :: Handle -> IO ()
+run inputFile = do
+  input <- hGetContents inputFile
+  case parse inputParser "<input>" input of
+    Left errorText -> print errorText
+    Right commands -> do
+      let isWater = \case MovingWater -> True
+                          StillWater -> True
+                          _ -> False
+          isStillWater = \case StillWater -> True
+                               _ -> False
+      let (solution1, solution2) = runST $ do
+            board <- buildBoard commands
+            flowWater board [(0, 500)]
+            res1 <- countCells board (findMinY commands) isWater
+            res2 <- countCells board (findMinY commands) isStillWater
+            return (res1, res2)
+      print solution1
+      print solution2

day17/stack.yaml

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+# This file was automatically generated by 'stack init'
+#
+# Some commonly used options have been documented as comments in this file.
+# For advanced use and comprehensive documentation of the format, please see:
+# https://docs.haskellstack.org/en/stable/yaml_configuration/
+
+# Resolver to choose a 'specific' stackage snapshot or a compiler version.
+# A snapshot resolver dictates the compiler version and the set of packages
+# to be used for project dependencies. For example:
+#
+# resolver: lts-3.5
+# resolver: nightly-2015-09-21
+# resolver: ghc-7.10.2
+#
+# The location of a snapshot can be provided as a file or url. Stack assumes
+# a snapshot provided as a file might change, whereas a url resource does not.
+#
+# resolver: ./custom-snapshot.yaml
+# resolver: https://example.com/snapshots/2018-01-01.yaml
+resolver: lts-13.1
+
+# User packages to be built.
+# Various formats can be used as shown in the example below.
+#
+# packages:
+# - some-directory
+# - https://example.com/foo/bar/baz-0.0.2.tar.gz
+# - location:
+#    git: https://github.com/commercialhaskell/stack.git
+#    commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+# - location: https://github.com/commercialhaskell/stack/commit/e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+#  subdirs:
+#  - auto-update
+#  - wai
+packages:
+- .
+# Dependency packages to be pulled from upstream that are not in the resolver
+# using the same syntax as the packages field.
+# (e.g., acme-missiles-0.3)
+# extra-deps: []
+
+# Override default flag values for local packages and extra-deps
+# flags: {}
+
+# Extra package databases containing global packages
+# extra-package-dbs: []
+
+# Control whether we use the GHC we find on the path
+# system-ghc: true
+#
+# Require a specific version of stack, using version ranges
+# require-stack-version: -any # Default
+# require-stack-version: ">=1.9"
+#
+# Override the architecture used by stack, especially useful on Windows
+# arch: i386
+# arch: x86_64
+#
+# Extra directories used by stack for building
+# extra-include-dirs: [/path/to/dir]
+# extra-lib-dirs: [/path/to/dir]
+#
+# Allow a newer minor version of GHC than the snapshot specifies
+# compiler-check: newer-minor