60 lines
1.9 KiB
Haskell
60 lines
1.9 KiB
Haskell
module Day5.Main where
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import System.IO
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import Data.List
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import Data.List.Split
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import Text.Regex.TDFA
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main :: IO ()
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main = do
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putStrLn "Day 5"
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handle <- openFile "app/Day5/input" ReadMode
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contents <- hGetContents handle
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let r1 = part1 contents
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putStrLn $ "part 1: " ++ r1
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let r2 = part2 contents
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putStrLn $ "part 2: " ++ r2
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return ()
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trim :: String -> String
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trim = unwords . words
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type Stack = [Char]
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type Instruction = (Int, Int, Int) -- count, from, to
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-- yea I'm not cleaning this up, I just glued this together in a repl
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parseData :: String -> ([Stack], [Instruction])
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parseData contents = (stacks, instructions)
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where
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parts = splitOn "\n\n" contents
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stacks = map (trim . snd) $ filter (\(i, _) -> i `mod` 4 == 2) $ zip [1..] (transpose $ init $ lines $ parts !! 0)
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instructions = map (\(a:b:c:_) -> (a,b-1,c-1)) $ map (\(_, _, _, m) -> map (read :: String -> Int) m) $ map ((=~ "move ([[:digit:]]+) from ([[:digit:]]+) to ([[:digit:]]+)") :: String -> (String, String, String, [String])) (lines $ parts !! 1)
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update :: Int -> a -> [a] -> [a]
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update n item ls = a ++ (item:b)
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where (a, (_:b)) = splitAt n ls
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executeInstructions :: Bool -> [Stack] -> [Instruction] -> [Stack]
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executeInstructions is9001 stacks [] = stacks
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executeInstructions is9001 stacks ((c,f,t):is) = executeInstructions is9001 stacks' is
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where
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from = stacks !! f
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to = stacks !! t
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items = (if is9001 then id else reverse) $ take c from
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from' = drop c $ from
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to' = items ++ to
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stacks' = update f from' $ update t to' stacks
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crane :: Bool -> String -> String
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crane is9001 contents = map (!! 0) stacks'
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where
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(stacks, instructions) = parseData contents
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stacks' = executeInstructions is9001 stacks instructions
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part1, part2 :: String -> String
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part1 = crane False
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part2 = crane True
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