How to accelerate this program?

[Li Jie]

In article <e0tkil$kkn$1 at digitaldaemon.com>, Lionello Lunesu says...
>
>Dave wrote:
>> From what I've seen, the bottleneck is probably in I/O. Use BufferedFile and a
>> buffer for each readline. 
>
>C's FILE and fopen also create a buffered stream, so I doubt that will 
>make a difference.
>
>But why the sort?? Try this instead:

Thanks.

It takes ~1800ms on my Gentoo, and ~2000ms on my Windows XP.