Difference between revisions of "Programming performance/ArthurVanLeeuwen Haskell"

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(comment about potential bug)
(Deleting page that hasn't been edited for over 10 years)
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Didn't feel like thinking at all, so this is a trivial recursive solution.
 
 
=== Code ===
 
 
<haskell>
 
main = do xs <- getContents
 
let cashheld = runStrategy 10000 . reverse . getDays . filter (\l -> head l /= '#') . filter (not . null) $ lines xs
 
putStrLn $ "Cash held: " ++ show cashheld
 
 
getDays :: [String] -> [(String,Double,Double,Double,Double,Integer,Double)]
 
getDays = map getDay
 
 
getDay :: String -> (String,Double,Double,Double,Double,Integer,Double)
 
getDay s = getDay' $ words s
 
where getDay' [date,open,high,low,close,volume,adjustedclose] = (date,read open,read high,read low,read close,read volume,read adjustedclose)
 
 
runStrategy cash lines = runStrategy' cash lines []
 
 
runStrategy' cash lines shares =
 
case lines of
 
(c1:c2:_) -> if (closing c2 - closing c1) / closing c1 < - 0.03 then
 
runStrategy' (cash * 0.9) (tail lines) ((((cash * 0.1) / closing c2), closing c2): shares)
 
else if not . null $ shares then
 
if (closing c2 - (snd . head $ shares)) / (snd . head $ shares) > 0.06 then
 
runStrategy' (cash + (fst . head $ shares) * closing c2) (tail lines) (tail shares)
 
else runStrategy' cash (tail lines) shares
 
else runStrategy' cash (tail lines) shares
 
[c1] -> cash + sellOff (closing c1) shares
 
[] -> cash
 
 
sellOff price shares = sum . map (* price) . map fst $ shares
 
 
closing (date,open,high,low,close,volume,adjustedclose) = close
 
</haskell>
 
 
* '''Bug/Question''': This solution will only perform one sale per day, even if multiple sales qualify, right? If recursion after a sale used lines instead of tail lines, then multiple sales could occur. [[User:Newsham|Newsham]] 18:08, 8 March 2007 (UTC)
 

Revision as of 14:09, 6 February 2021