20 lines
814 B
Haskell
20 lines
814 B
Haskell
import Data.IntMap (IntMap, insert, fromList, findWithDefault)
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type State = (Int, Int, IntMap Int)
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type Update = Int -> Int
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next :: Update -> State -> State
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next f (steps, i, jumps) =
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let value = findWithDefault undefined i jumps
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in (steps + 1, i + value, insert i (f value) jumps)
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getExitSteps :: Int -> Update -> State -> Int
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getExitSteps len f (steps, i, jumps) =
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if i >= len then steps else getExitSteps len f $! next f (steps, i, jumps)
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main :: IO ()
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main = do
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jumpsList <- fmap (map read . lines) $ readFile "5.txt"
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let jumpsMap = fromList $ zip [0..] jumpsList
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print $ getExitSteps (length jumpsList) (+1) (0, 0, jumpsMap)
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print $ getExitSteps (length jumpsList) (\v -> if v >= 3 then v - 1 else v + 1) (0, 0, jumpsMap) |