42 lines
1.9 KiB
Haskell
42 lines
1.9 KiB
Haskell
{-# LANGUAGE ScopedTypeVariables #-}
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import Data.Char
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import Data.List.Split
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import Data.List
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import Data.Maybe
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main = do
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ls <- readFile "5.in"
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putStrLn . show . solve . parse $ ls where
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solve (ss, ms) = map head . applyMovesA (map (map ((+)(-1))) ms) . map (filter (/=' ')) $ buildStacks ss where
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--solveB (ss, ms) = map head . applyMovesB (map (map ((+)(-1))) ms) . map (filter (/=' ')) $ buildStacks ss
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size = length $ ss !! 0
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buildStacks :: [[Char]] -> [[Char]]
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buildStacks (x: xs) = zipWith (:) x (buildStacks xs)
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buildStacks [] = replicate size []
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parse = parseStacksAndMoves . take 2 . map lines . splitOn "\n\n" where
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parseStacksAndMoves [ss, ms] = (filter ((/='1') . (!!0) ) $ parseStacks ss, parseMoves ms)
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parseStacks = map split3 where
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split3 (a:b:c:[]) = b : []
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split3 (a:b:c:' ':xs) = b : (split3 xs)
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split3 (_) = []
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parseMoves = map (map parseInt . getNums . words) where
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getNums x = [x !! 1, x !! 3, x !! 5]
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parseInt = read :: String -> Int
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applyMovesA moves stacks = foldl applyMove stacks moves where
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applyMove stacks [count, from, to] = iterate (moveOne from to) stacks !! (count + 1)
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moveOne from to stack = moveMany 0 from to stack
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applyMovesB moves stacks = foldl applyMove stacks moves where
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applyMove stacks [count, from, to] = moveMany count from to stacks
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moveMany count from to stack = updateStack from to stack where
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newItems = take (count +1) $ (stack !! from)
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updateStack :: Int -> Int -> [[Char]] -> [[Char]]
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updateStack from to (x:xs) | from == 0 = (iterate tail x !! (count + 1)) : (updateStack (from - 1) (to - 1) xs)
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updateStack from to (x:xs) | to == 0= (newItems ++ x) : (updateStack (from - 1) (to - 1) xs)
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updateStack from to (x:xs) = x : (updateStack (from - 1) (to - 1) xs)
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updateStack from to [] = []
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