Jun 2004
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Jun 2004
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overwise
Jun '04

Hello, there!

There are obviously some problems with the linkage of the default ghc libraries at the system judge.
I tried to use the Text.ParserCombinators.Parsec.Expr module for solving problem 4 (Transform the Expression). But I got compile errors from the linker.
Are there any special hierarchical qualifiers I have to adhere to? Or is it just, that there libraries aren't properly installed?

thx

cu,
robin

noix
Jun '04

It seems the compiler really is broken.
It will be replaced with a new one, probably tomorrow.

Thanks for the info.

noix
Jun '04

We use ghc 5.04.3 now, with -O switch (-O0 before).
A few of your solutions had been retested. Only one AC, though, and two dreaded TLEs.

I checked your "Complicated Expressions" solution, I had to allow about 80 megs of ram and it ran over a minute (giving WA in the end, it didn't omit some parentheses, by the way). So adjusting time limits can't be the solution for some problems..

system
Jun '04

I suppose, you tested my first submission of the problem (there was a minor bug in it - added one line and submitted it again on 2004-06-17 00:00:01 [submission number 1655]).
I checked the efficiency myself on the original judge input from the problem source. On the slower of the two computers (500 MHz) it ran 24 sec giving a correct result.
As for the memory usage, this is a natural problem of functional programming, because you have to do almost everything recursively.

But I will try to write a faster IO routine which uses less memory, because I think I am not far away from an acceptable solution...

noix
Jun '04

Yes it was that one smile I didn't notice the latter was different.

I tried that solution with an extended time limit and it gave an AC in 72 seconds (it didn't need extending memory limit now). I think we can't extend time limit so much (it's 20s now), probably some brute force programs in C would start to get AC..
The PC all programs are ran on now is Pentium 166 MMX, by the way.

Yes, but it's not such a big problem as time limits; few problems become much easier given enough memory.. Right now, memory limits shown in problem's description are always increased by a ~40MB to allow all interpreters (especially java) to run. Later, probably a special flag for problems will be introduced, saying the memory limit is playing a key role and is not extended and it is solvable only in a few chosen languages.