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|
{-# LANGUAGE DeriveGeneric #-}
--------------------------------------------------------------------------------
module Main where
--------------------------------------------------------------------------------
import Data.Hashable
import Data.Function ((&))
import GHC.Generics
import Text.ParserCombinators.ReadP
import Control.Applicative
import qualified Data.HashSet as HS
--------------------------------------------------------------------------------
data Direction
= DirLeft
| DirRight
| DirUp
| DirDown
deriving (Eq, Show)
data Point = Point Int Int
deriving (Eq, Show, Ord, Generic)
instance Hashable Point
data Orientation
= Horizontal
| Vertical
deriving (Eq, Show)
data Anchor
= Beg
| End
deriving (Eq, Show)
data Rotation
= CW
| CCW
deriving (Eq, Show)
data Line = Line Point Point
deriving (Show, Generic)
instance Hashable Line
instance Eq Line where
Line begA endA == Line begB endB =
(begA == begB && endA == endB) ||
(begA == endB && endA == begB)
data Game = Game (HS.HashSet Line) [Line]
deriving (Eq, Show)
data Scoreboard = Scoreboard Int Int
deriving (Eq)
instance Semigroup Scoreboard where
(Scoreboard a b) <> (Scoreboard x y) =
Scoreboard (a + x) (b + y)
instance Monoid Scoreboard where
mempty = Scoreboard 0 0
data Turn
= Player1
| Player2
deriving (Eq, Show)
next :: Turn -> Turn
next Player1 = Player2
next Player2 = Player1
instance Show Scoreboard where
show (Scoreboard p1 p2) =
"Player 1: " ++ show (p1) ++ " Player 2: " ++ show (p2)
digit :: ReadP Char
digit = satisfy (\c -> c >= '0' && c <= '9')
int :: ReadP Int
int = read <$> many1 digit
inputLine :: ReadP String
inputLine = manyTill get (char '\n')
direction :: ReadP Direction
direction = do
c <- char 'L' <|> char 'R' <|> char 'U' <|> char 'D'
case c of
'L' -> pure DirLeft
'R' -> pure DirRight
'U' -> pure DirUp
'D' -> pure DirDown
_ -> fail $ "Unexpected direction: " ++ show c
validMove :: Int -> Int -> ReadP Line
validMove w h = do
x <- int
skipSpaces
y <- int
skipSpaces
dir <- direction
_ <- char '\n'
if x >= 0 && x <= w && y >= 0 && y <= h then do
let beg = Point x y
pure $ mkLine beg (shiftPoint dir beg)
else
fail "Expected a move on the game board"
game :: ReadP Game
game = do
w <- read <$> inputLine
h <- read <$> inputLine
locs <- read <$> inputLine
moves <- count locs (validMove w h)
eof
pure $ Game mempty moves
parseInput :: String -> Maybe Game
parseInput x = do
case readP_to_S game x of
[(res, "")] -> Just res
_ -> Nothing
-- | Smart constructor to ensure that beg is always < end.
mkLine :: Point -> Point -> Line
mkLine beg end =
if beg < end then Line beg end else Line end beg
mkLineDir :: Int -> Int -> Direction -> Line
mkLineDir x y dir =
let beg = Point x y
in mkLine beg (shiftPoint dir beg)
mkLineDir' :: Point -> Direction -> Line
mkLineDir' (Point x y) dir = mkLineDir x y dir
shiftPoint :: Direction -> Point -> Point
shiftPoint DirLeft (Point x y) = Point (x - 1) y
shiftPoint DirRight (Point x y) = Point (x + 1) y
shiftPoint DirUp (Point x y) = Point x (y + 1)
shiftPoint DirDown (Point x y) = Point x (y - 1)
shiftLine :: Direction -> Line -> Line
shiftLine dir (Line beg end) =
mkLine (shiftPoint dir beg) (shiftPoint dir end)
rotateLine :: Anchor -> Rotation -> Line -> Line
rotateLine anchor rotation line =
doRotateLine (classifyOrientation line) anchor rotation line
doRotateLine :: Orientation -> Anchor -> Rotation -> Line -> Line
doRotateLine Horizontal Beg CW (Line beg _) = mkLineDir' beg DirDown
doRotateLine Horizontal Beg CCW (Line beg _) = mkLineDir' beg DirUp
doRotateLine Horizontal End CW (Line _ end) = mkLineDir' end DirUp
doRotateLine Horizontal End CCW (Line _ end) = mkLineDir' end DirDown
doRotateLine Vertical Beg CW (Line beg _) = mkLineDir' beg DirRight
doRotateLine Vertical Beg CCW (Line beg _) = mkLineDir' beg DirLeft
doRotateLine Vertical End CW (Line _ end) = mkLineDir' end DirLeft
doRotateLine Vertical End CCW (Line _ end) = mkLineDir' end DirRight
classifyOrientation :: Line -> Orientation
classifyOrientation (Line (Point _ y1) (Point _ y2)) =
if y1 == y2 then Horizontal else Vertical
closesAnySquare :: HS.HashSet Line -> Line -> Bool
closesAnySquare allMoves line = do
let alreadyDrawn x = HS.member x allMoves
case classifyOrientation line of
Horizontal ->
all alreadyDrawn
[ shiftLine DirUp line
, rotateLine Beg CCW line
, rotateLine End CW line
] ||
all alreadyDrawn
[ shiftLine DirDown line
, rotateLine Beg CW line
, rotateLine End CCW line
]
Vertical ->
all alreadyDrawn
[ shiftLine DirLeft line
, rotateLine Beg CCW line
, rotateLine End CW line
] ||
all alreadyDrawn
[ shiftLine DirRight line
, rotateLine Beg CW line
, rotateLine End CCW line
]
incScoreboard :: Turn -> Scoreboard -> Scoreboard
incScoreboard Player1 score = score <> Scoreboard 1 0
incScoreboard Player2 score = score <> Scoreboard 0 1
scoreGame :: Turn -> Game -> Scoreboard -> Maybe Scoreboard
scoreGame _ (Game _ []) score = Just $ score
scoreGame player (Game allMoves (line:rest)) score =
if HS.member line allMoves then
Nothing
else do
let allMoves' = HS.insert line allMoves
score' = if closesAnySquare allMoves line then
incScoreboard player score
else score
scoreGame (next player) (Game allMoves' rest) score'
(|>) :: a -> (a -> b) -> b
(|>) = (&)
main :: IO ()
main = do
input <- readFile "game.txt"
case parseInput input of
Nothing -> putStrLn "invalid"
Just parsedGame ->
case scoreGame Player1 parsedGame mempty of
Nothing -> putStrLn "invalid"
Just score -> print score
|
