X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=adventofcode16%2Fapp%2Fadvent15l.hs;fp=adventofcode16%2Fapp%2Fadvent15l.hs;h=67e2ac07e4a85d295765de50f6b42343b7818f24;hb=fd498a2713d69a5d55179ff07e58ce296d6fba94;hp=0000000000000000000000000000000000000000;hpb=3a26b187d5dc23b05fb73daabe52a92976a7a3c7;p=advent-of-code-16.git

diff --git a/adventofcode16/app/advent15l.hs b/adventofcode16/app/advent15l.hs
new file mode 100644
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+++ b/adventofcode16/app/advent15l.hs
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+module Main(main) where
+
+import Text.Parsec 
+import Text.ParserCombinators.Parsec.Number
+
+main :: IO ()
+main = do 
+    text <- readFile "data/advent15.txt" 
+    let disks = successfulParse $ parseIfile text
+    part1 disks
+    part2 disks
+
+part1 :: [[Int]] -> IO ()
+part1 disks = print $ head $ filter (canFall disks) [0..]
+
+part2 :: [[Int]] -> IO ()
+part2 disks = print $ head $ filter (canFall disks2) [0..]
+    where disks2 = disks ++ [drop 7 $ drop 0 $ cycle [0..(11-1)]]
+
+canFall :: [[Int]] -> Int -> Bool
+canFall ds i = all (\d -> (d!!i) == 0) ds
+
+
+instructionFile = instructionLine `endBy` newline 
+instructionLine = diskify <$> (string "Disc #" *> int) 
+                          <*> (string " has " *> int)
+                          <*> (string " positions; at time=0, it is at position " *> int)
+                          <*  (string ".")
+                    where diskify n size pos0 = drop n $ drop pos0 $ cycle [0..(size-1)]
+
+parseIfile :: String -> Either ParseError [[Int]]
+parseIfile input = parse instructionFile "(unknown)" input
+
+parseIline :: String -> Either ParseError [Int]
+parseIline input = parse instructionLine "(unknown)" input
+
+successfulParse :: Either ParseError [a] -> [a]
+successfulParse (Left _) = []
+successfulParse (Right a) = a