Here it is

One problem I've had getting started with roguelikes is coming up with a decent, flexible data structure that can be used to store the locations of characters/items/objects.

My container allows for many objects to exist at one cell, and has relatively quick lookup speed by cell, and log(n) lookup speed by objects. (EDIT: After some suggestions, I believe it now runs in O(1) time for all operations!)

Would love it if anyone could critique or provide suggestions!

This is quite a small project of course, but lately I've been trying to work on small, polished projects rather than huge projects that I never finish. I figure if I start small, I'll eventually be able to make a full game that I'm happy with! Doing things this way means I also get to see something through to the end and make sure I'm happy with the quality of it before continuing. It also encourages me to really make sure something works well before continuing onto something new, hopefully meaning less design problems later.