38 lines
1.2 KiB
Haskell
38 lines
1.2 KiB
Haskell
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import Data.Foldable
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import Data.HashSet
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import Data.Sequence
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type Bank = Seq Int
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type Config = (Bank, Data.HashSet.HashSet [Int])
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(%) :: Int -> Int -> Int
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(%) = mod
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getMaxMem :: Bank -> (Int, Int)
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getMaxMem bank =
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foldlWithIndex (\(currIndex, currMax) index value -> if value > currMax then (index, value) else (currIndex, currMax)) (0, 0) bank
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nextBank :: Bank -> Bank
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nextBank bank =
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let len = Data.Sequence.length bank
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(index, value) = getMaxMem bank
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zeroedBank = update index 0 bank
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mappedBank = fmap (+ value `div` len) zeroedBank
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indicesToUpdate = fmap (% len) [(index + 1)..(index + value % len)]
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in mapWithIndex (\i v -> if i `elem` indicesToUpdate then v + 1 else v) mappedBank
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cycles :: Int -> Config -> Int
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cycles count (prevBank, configs) =
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let bank = nextBank prevBank
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hashableBank = Data.Foldable.toList bank
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in if member hashableBank configs
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then count + 1
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else cycles (count + 1) (bank, insert hashableBank configs)
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main :: IO ()
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main = do
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input <- readFile "6.txt"
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let bank = Data.Sequence.fromList $ fmap read $ words input :: Bank
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print $ cycles 0 (bank, Data.HashSet.empty)
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