27 lines
946 B
Haskell
27 lines
946 B
Haskell
import Data.IntMap (IntMap, insert, fromList, findWithDefault)
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type Length = Int
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type Index = Int
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type Steps = Int
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type State = (Steps, Index, 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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nextI = i + value
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nextJumps = insert i (f value) jumps
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in (steps + 1, nextI, nextJumps)
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getExitSteps :: Length -> 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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input <- readFile "5.txt"
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let jumpsList = map read $ lines input
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jumpsMap = fromList $ zip [0..] jumpsList
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len = length jumpsList
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print $ getExitSteps len (+1) (0, 0, jumpsMap)
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print $ getExitSteps len (\v -> if v >= 3 then v - 1 else v + 1) (0, 0, jumpsMap) |