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2017
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Day 5 - replaced Seq Int with IntMap Int for slight performance improvement...

This commit is contained in:
Jonathan Chan 2017-12-06 20:38:38 -08:00
parent f395778a9f
commit e910558507
1 changed files with 13 additions and 10 deletions
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23
5.hs
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@ -1,24 +1,27 @@
import Data.Sequence import Data.IntMap (IntMap, insert, size, fromList, findWithDefault)
type Length = Int
type Index = Int type Index = Int
type Steps = Int type Steps = Int
type State = (Steps, Index, Seq Int) type State = (Steps, Index, IntMap Int)
type Update = Int -> Int type Update = Int -> Int
next :: Update -> State -> State next :: Update -> State -> State
next f (steps, i, jumps) = next f (steps, i, jumps) =
let value = index jumps i let value = findWithDefault undefined i jumps
nextI = i + value nextI = i + value
nextJumps = update i (f value) jumps nextJumps = insert i (f value) jumps
in (steps + 1, nextI, nextJumps) in (steps + 1, nextI, nextJumps)
getExitSteps :: Update -> State -> Int getExitSteps :: Length -> Update -> State -> Int
getExitSteps f (steps, i, jumps) = getExitSteps len f (steps, i, jumps) =
if i >= Data.Sequence.length jumps then steps else getExitSteps f $ next f (steps, i, jumps) if i >= len then steps else getExitSteps len f $ next f (steps, i, jumps)
main :: IO () main :: IO ()
main = do main = do
input <- readFile "5.txt" input <- readFile "5.txt"
let jumps = fromList . map read $ lines input :: Seq Int let jumpsList = map read $ lines input
print $ getExitSteps (+1) (0, 0, jumps) jumpsMap = fromList $ zip [0..] jumpsList
print $ getExitSteps (\v -> if v >= 3 then v - 1 else v + 1) (0, 0, jumps) len = length jumpsList
print $ getExitSteps len (+1) (0, 0, jumpsMap)
print $ getExitSteps len (\v -> if v >= 3 then v - 1 else v + 1) (0, 0, jumpsMap)