- {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE OverloadedStrings #-}
- import Data.List
+import Data.List
- import Data.Text (Text)
- import qualified Data.Text.IO as TIO
+import Data.Text (Text)
+import qualified Data.Text.IO as TIO
- import Data.Void (Void)
+import Data.Void (Void)
- import Text.Megaparsec
- import Text.Megaparsec.Char
- import qualified Text.Megaparsec.Char.Lexer as L
- import qualified Control.Applicative as CA
+import Text.Megaparsec
+import Text.Megaparsec.Char
+import qualified Text.Megaparsec.Char.Lexer as L
+import qualified Control.Applicative as CA
- import qualified Data.Map.Strict as M
+import qualified Data.Map.Strict as M
- type Coord = (Integer, Integer) -- x, y
- type Bounds = (Integer, Integer, Integer, Integer) -- minX, maxX, minY, maxY
- type Region = M.Map Coord Int
+type Coord = (Integer, Integer) -- x, y
+type Bounds = (Integer, Integer, Integer, Integer) -- minX, maxX, minY, maxY
+type Region = M.Map Coord Int
- main :: IO ()
- main = do
- text <- TIO.readFile "data/advent06.txt"
- let coords = successfulParse text
- let boundingBox = findBounds coords
- print $ length coords
- print boundingBox
- print $ part1 coords boundingBox
- print $ part2 coords boundingBox
+main :: IO ()
+main = do
+ text <- TIO.readFile "data/advent06.txt"
+ let coords = successfulParse text
+ let boundingBox = findBounds coords
+ print $ part1 coords boundingBox
+ print $ part2 coords boundingBox
- part1 coords bounds = largestRegion $ regionSizes $ finite edgeLabels regions
- where regions = findRegions coords bounds
- edgeLabels = infinite regions bounds
+part1 coords bounds = largestRegion $ regionSizes $ finite edgeLabels regions
+ where regions = findRegions coords bounds
+ edgeLabels = infinite regions bounds
- part2 coords bounds = M.size $ M.filter (< 10000) $ safeCells coords bounds
+part2 coords bounds = M.size $ M.filter (< 10000) $ safeCells coords bounds
- findRegions :: [Coord] -> Bounds -> Region
- findRegions coords (minX, maxX, minY, maxY) = M.fromList labelledCells
- where cells = [(x, y) | x <- [minX .. maxX], y <- [minY .. maxY] ]
- starts = zip [1..] coords
- labelledCells = map (\c -> (c, nearestStart 0 c starts)) cells
+findRegions :: [Coord] -> Bounds -> Region
+findRegions coords (minX, maxX, minY, maxY) = M.fromList labelledCells
+ where cells = [(x, y) | x <- [minX .. maxX], y <- [minY .. maxY] ]
+ starts = zip [1..] coords
+ labelledCells = map (\c -> (c, nearestStart 0 c starts)) cells
- nearestStart :: Int -> Coord -> [(Int, Coord)] -> Int
- nearestStart tieLabel cell starts = nearestLabel
- where distances = sort $ map (\(l, s) -> (distance s cell , l)) starts
- nearestLabel = if fst (distances!!0) == fst (distances!!1)
- then tieLabel
- else snd (distances!!0)
+nearestStart :: Int -> Coord -> [(Int, Coord)] -> Int
+nearestStart tieLabel cell starts = nearestLabel
+ where distances = sort $ map (\(l, s) -> (distance s cell , l)) starts
+ nearestLabel = if fst (distances!!0) == fst (distances!!1)
+ then tieLabel
+ else snd (distances!!0)
+safeCells :: [Coord] -> Bounds -> Region
+safeCells coords (minX, maxX, minY, maxY) = M.fromList distanceCells
+ where cells = [(x, y) | x <- [minX .. maxX], y <- [minY .. maxY] ]
+ distanceCells = map (\c -> (c, fromIntegral $ sumDistance c coords) ) cells
- safeCells :: [Coord] -> Bounds -> Region
- safeCells coords (minX, maxX, minY, maxY) = M.fromList distanceCells
- where cells = [(x, y) | x <- [minX .. maxX], y <- [minY .. maxY] ]
- distanceCells = map (\c -> (c, fromIntegral $ sumDistance c coords) ) cells
+sumDistance :: Coord -> [Coord] -> Integer
+sumDistance here others = sum $ map (\c -> distance here c) others
+infinite :: Region -> Bounds -> [Int]
+infinite regions (minX, maxX, minY, maxY) = nub $ sort $ M.elems $ M.filterWithKey onEdge regions
+ where onEdge (x, y) _ = (x == minX) || (x == maxX) || (y == minY) || (y == maxY)
- sumDistance :: Coord -> [Coord] -> Integer
- sumDistance here others = sum $ map (\c -> distance here c) others
+finite :: [Int] -> Region -> Region
+finite excluded regions = M.filter (\r -> r `notElem` excludedTied) regions
+ where excludedTied = (0:excluded)
+regionSizes :: Region -> [(Int, Int)]
+regionSizes regions = map (\g -> (g!!0, length g)) $ group $ sort $ M.elems regions
- infinite :: Region -> Bounds -> [Int]
- infinite regions (minX, maxX, minY, maxY) = nub $ sort $ M.elems $ M.filterWithKey onEdge regions
- where onEdge (x, y) _ = (x == minX) || (x == maxX) || (y == minY) || (y == maxY)
+largestRegion :: [(Int, Int)] -> Int
+largestRegion = maximum . map snd
- finite :: [Int] -> Region -> Region
- finite excluded regions = M.filter (\r -> r `notElem` excludedTied) regions
- where excludedTied = (0:excluded)
+findBounds :: [Coord] -> (Integer, Integer, Integer, Integer)
+findBounds coords = ( minX - (maxY - minY) `div` 2 -- small x edge
+ , maxX + (maxY - minY) `div` 2 -- large x edge
+ , minY - (maxX - minX) `div` 2-- small x edge
+ , maxY + (maxX - minX) `div` 2 -- large y edge
+ )
+ where maxX = maximum $ map fst coords
+ minX = minimum $ map fst coords
+ maxY = maximum $ map snd coords
+ minY = minimum $ map snd coords
- regionSizes :: Region -> [(Int, Int)]
- regionSizes regions = map (\g -> (g!!0, length g)) $ group $ sort $ M.elems regions
+-- Manhattan distance
+distance :: Coord -> Coord -> Integer
+distance (x1, y1) (x2, y2) = (abs (x1 - x2)) + (abs (y1 - y2))
- largestRegion :: [(Int, Int)] -> Int
- largestRegion = maximum . map snd
+-- Parse the input file
+type Parser = Parsec Void Text
- findBounds :: [Coord] -> (Integer, Integer, Integer, Integer)
- findBounds coords = ( minX - (maxY - minY) `div` 2 -- small x edge
- , maxX + (maxY - minY) `div` 2 -- large x edge
- , minY - (maxX - minX) `div` 2-- small x edge
- , maxY + (maxX - minX) `div` 2 -- large y edge
- )
- where maxX = maximum $ map fst coords
- minX = minimum $ map fst coords
- maxY = maximum $ map snd coords
- minY = minimum $ map snd coords
+sc :: Parser ()
+sc = L.space (skipSome spaceChar) CA.empty CA.empty
- -- Manhattan distance
- distance :: Coord -> Coord -> Integer
- distance (x1, y1) (x2, y2) = (abs (x1 - x2)) + (abs (y1 - y2))
+lexeme = L.lexeme sc
+integer = lexeme L.decimal
+symb = L.symbol sc
+commaP = symb ","
- -- Parse the input file
+coordFileP = many coordP
+coordP = (,) <$> integer <* commaP <*> integer
- type Parser = Parsec Void Text
-
- sc :: Parser ()
- sc = L.space (skipSome spaceChar) CA.empty CA.empty
- -- sc = L.space (skipSome (char ' ')) CA.empty CA.empty
-
- lexeme = L.lexeme sc
- integer = lexeme L.decimal
- symb = L.symbol sc
-
- commaP = symb ","
-
-
- coordFileP = many coordP
- coordP = (,) <$> integer <* commaP <*> integer
-
- successfulParse :: Text -> [Coord]
- successfulParse input =
- case parse coordFileP "input" input of
- Left _error -> [] -- TIO.putStr $ T.pack $ parseErrorPretty err
- Right coords -> coords
\ No newline at end of file
+successfulParse :: Text -> [Coord]
+successfulParse input =
+ case parse coordFileP "input" input of
+ Left _error -> [] -- TIO.putStr $ T.pack $ parseErrorPretty err
+ Right coords -> coords
\ No newline at end of file