In reply to RENCFanesto:
You would need to give a lot more information for anyone to offer a good suggestion. Do you actually have 100K inputs, or is this encoded into some address?
If you are going to access each input, why do you need a sparse (associative) array?
Also need a better description of “neighborhoods” how many are there? do they overlap?
You will most likely need to create some helper logic as trying to cover this within a covergroup might be problematic.