This one comes via Vikram Subbaiah on the forum.
In simple terms, it will detect what level a room is on and then automatically generate and apply a suitable room number.
Related downloads:
Workflow: Automatically Renumber Rooms with Level Detection
Dynamo Nodes 
Hello, i`m newbie in Dynamo.
In first thanks for a script. May i associate prefix of number by parameters?
In case i have flat number 1, and 5 rooms have parameter “number of flat” value also “1”
Can script automate numbering prefix only for rooms which contains identical value?
Thx for any ideas.