module Main(main) where
-import Text.Parsec hiding (State)
--- import Text.ParserCombinators.Parsec.Number
-
-
+import Data.List (tails)
main :: IO ()
main = do
- text <- readFile "data/advent01.txt"
- let instructions = successfulParse $ parseIline text
- part1 instructions
- part2 instructions
-
-part1 :: [Int] -> IO ()
-part1 instructions = do
- print $ sum instructions
-
-part2 :: [Int] -> IO ()
-part2 instructions = do
- print $ length $ takeWhile (>= 0) $ scanl (+) 0 instructions
-
-
-
--- instructionFile = instructionLine `endBy` newline
-instructionLine = many (up <|> down)
+ digits <- readFile "data/advent01.txt"
+ print $ part1 digits
+ print $ part2 digits
+part1 :: String -> Integer
+part1 = sum_valid_pairs . part1_extract
-up = char '(' *> pure 1
-down = char ')' *> pure -1
+part2 :: String -> Integer
+part2 = sum_valid_pairs . part2_extract
--- parseIfile :: String -> Either ParseError [[Int]]
--- parseIfile input = parse instructionFile "(unknown)" input
+part1_extract :: String -> [String]
+part1_extract digits = map (take 2) $ tails (digits ++ [head digits])
-parseIline :: String -> Either ParseError [Int]
-parseIline input = parse instructionLine "(unknown)" input
+part2_extract :: String -> [String]
+part2_extract digits = map (\ds -> (take 1 ds) ++ (take 1 $ drop offset ds))
+ $ take (length digits)
+ $ tails (digits ++ digits)
+ where offset = length digits `div` 2
-successfulParse :: Either ParseError [a] -> [a]
-successfulParse (Left _) = []
-successfulParse (Right a) = a
+sum_valid_pairs :: [String] -> Integer
+sum_valid_pairs possibles = sum $ map (read . take 1)
+ $ filter (\(x:y:_) -> x == y)
+ $ filter (\p -> length p == 2) possibles
\ No newline at end of file