dons:
mdanish:
Hello,
I've been playing with the INTEST problem on SPOJ which demonstrates the ability to write a program which processes large quantities of input data. http://www.spoj.pl/problems/INTEST/
But when I make a slight modification, the program chews up a ton more memory and takes more time:
import Control.Monad import Data.Maybe import qualified Data.ByteString.Char8 as B
divisibleBy :: Int -> Int -> Bool a `divisibleBy` n = a `rem` n == 0
main :: IO () main = do [n,k] <- (map int . B.split ' ') `fmap` B.getLine :: IO [Int]
let doLine :: Int -> Int -> IO Int doLine r _ = B.getLine >>= return . testDiv r -- 'return' moved here ^^
And just following up with some GC statistics: Original, 95% cpu 1.668 total <<ghc: 258766440 bytes, 452 GCs, 3036/3036 avg/max bytes residency (1 samples), 3M in use, 0.00 INIT (0.00 elapsed), 1.51 MUT (1.63 elapsed), 0.01 GC (0.03 elapsed) :ghc>> Too lazy: 96% cpu 4.219 total <<ghc: 278683532 bytes, 495 GCs, --> 14729345/52642396 avg/max bytes residency (7 samples), --> 85M in use, 0.00 INIT (0.00 elapsed), 1.68 MUT (1.81 elapsed), --> 2.07 GC (2.36 elapsed) :ghc>> (clear space leak) Fixing above program with $!: 94% cpu 1.656 total <<ghc: 257394052 bytes 451 GCs, --> 2288/2288 avg/max bytes residency (1 samples), --> 1M in use, 0.00 INIT (0.00 elapsed), 1.49 MUT (1.64 elapsed), 0.01 GC (0.01 elapsed) :ghc>> Using lazy bytestrings for pure processing: 90% cpu 1.424 total <<ghc: 219403252 bytes, 410 GCs, 70527/74236 avg/max bytes residency (10 samples), 2M in use, 0.00 INIT (0.00 elapsed), 1.25 MUT (1.40 elapsed), 0.01 GC (0.01 elapsed) :ghc>> And the killer strict chunk parser: 78% cpu 0.327 total <<ghc: 20685092 bytes, --> 38 GCs, --> 81348/81348 avg/max bytes residency (1 samples), 2M in use, 0.00 INIT (0.00 elapsed), --> 0.21 MUT (0.32 elapsed), 0.00 GC (0.00 elapsed) :ghc>> Very little data shuffled around in the last one. -- Don