Sometimes when I get the urge to post a new challenge, I have trouble finding a notable* problem that has not yet been solved upon which to base my challenge (I'm not very creative). I thought it might be cool if we could generate a list of such problems here.
Here are some examples that I tried to find using the search box on Code Golf.
Here is one example of a problem that has been used before (many times).
- Shortest Path
Please post notable* problems that have not yet been touched. Post as many as you can think of. Correct other answers (and this question) if you see one that has been used before, but make sure that you provide a link.
If you decide to use one of the problems, leave a comment saying that you took it and link to the challenge.
*A notable problem is one that has been discussed in Academia as opposed to one you just thought of.