Algorithm? Runtime complexity?

[redbar0n]

Could you say something in the README about the algorithm you've chosen, and specifically about its runtime complexity (in big O notation)?

From csp.py I infer that it is some kind of backtracking, using MRV (minimum-remaining-values) and LCV (least-constraining-value) heuristics. I could not deduce if you use the so called "Degree heuristic" as well:

“Degree heuristic” – choose the variable that is part of the most remaining unsatisfied constraints. Useful to select first variable to assign.

Sources:
https://cs.stackexchange.com/questions/47870/what-is-least-constraining-value
http://pami.uwaterloo.ca/~basir/ECE457/week5.pdf