It's not a challange, when you produce only correct output. Many NP-hard problems have exponential time solutions, does it mean that we should accept them?? Time complexity is very important, and the way to force an appropriate complexity of the solution (via online judge) is to limit the execution time....
Yes, you are right, that's the price!
If only we get faster computers (next academic year), we'll try to overcome this problem.
Another solution: the problemsetter duplicates a selected problem with only a few languages, any suggestions?
Of course, this is a bit unfair towards users not programming in such languages like Haskell or Python, but on the other hand, if you wanted to solve it in such a language, you could do it!
Multiplying execution time, or using different time limits depending on the language is, in my opinion, unfair and impartial...
Finally, it's worth noting, that some problems support functional solutions, but others do not...
best regards,
mima