X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=adventofcode16%2Fapp%2Fadvent15.hs;fp=adventofcode16%2Fapp%2Fadvent15.hs;h=5970bd661c191054a14faf51896bfe441e13d4fc;hb=fd498a2713d69a5d55179ff07e58ce296d6fba94;hp=0000000000000000000000000000000000000000;hpb=3a26b187d5dc23b05fb73daabe52a92976a7a3c7;p=advent-of-code-16.git

diff --git a/adventofcode16/app/advent15.hs b/adventofcode16/app/advent15.hs
new file mode 100644
index 0000000..5970bd6
--- /dev/null
+++ b/adventofcode16/app/advent15.hs
@@ -0,0 +1,43 @@
+module Main(main) where
+
+import Text.Parsec 
+import Text.ParserCombinators.Parsec.Number
+
+type Disk = (Int -> Bool)
+
+main :: IO ()
+main = do 
+    text <- readFile "data/advent15.txt" 
+    let disks = successfulParse $ parseIfile text
+    part1 disks
+    part2 disks
+
+part1 :: [Disk] -> IO ()
+part1 disks = print $ head $ filter (canFall disks) [0..]
+
+part2 :: [Disk] -> IO ()
+part2 disks = print $ head $ filter (canFall disks2) [0..]
+    where disks2 = disks ++ [diskify 7 11 0]
+
+canFall :: [Disk] -> Int -> Bool
+canFall ds i = all (\d -> (d i)) ds
+
+
+instructionFile = instructionLine `endBy` newline 
+instructionLine = diskify <$> (string "Disc #" *> int) 
+                          <*> (string " has " *> int)
+                          <*> (string " positions; at time=0, it is at position " *> int)
+                          <*  (string ".")
+
+diskify :: Int -> Int -> Int -> (Int -> Bool)
+diskify n size pos0 = (\i -> (size + n + pos0 + i) `mod` size == 0)
+
+parseIfile :: String -> Either ParseError [Disk]
+parseIfile input = parse instructionFile "(unknown)" input
+
+parseIline :: String -> Either ParseError Disk
+parseIline input = parse instructionLine "(unknown)" input
+
+successfulParse :: Either ParseError [a] -> [a]
+successfulParse (Left _) = []
+successfulParse (Right a) = a