Puzzle repetition

[visvi]

Hi Zuril! I want to ask you, if it is somehow possible to not solve one problem twice? I mean, that when I have already done for example problem number 345, it sometimes happen, that after two, three days the system serves me the same problem again, and I remember solution, so this is no fun I suppose, that you supply server with new puzzles quite often, so it is better to use every problem only once, but each of them. Thanks a lot for answer! visvi

[Zuril]

I need too space in the database to store all problems attempted for all the users.
The random number generator in computer science is not a really random one...