[Haskell-beginners] Performance of Prime Generator

[Burton Samograd]

Zhi-Qiang Lei <zhiqiang.lei at gmail.com> writes:
> I have bungled the Prime Generator on SPOJ for many times. Although
> the program is faster and faster on my machine, but it keeps "time
> limited exceeded" on SPOJ (6 seconds limit). Now my approach is for
> every number in the range, check if it is prime by checking if can be
> divided by all the primes smaller than or equal its square root. For
> the numbers between 999900000 and 1000000000, it take 0.64 seconds on
> my laptop. Could anyone give me some hints to enhance it? Thanks.

There are some pretty good examples of fast prime generators here:

http://www.haskell.org/haskellwiki/Prime_numbers

although using them for SPOJ is a bit like cheating :)  I learned a lot
from that page though, so I advise giving it a good readover.

--
Burton Samograd
http://kruhft.dyndns.org