Adding info about time complexity

[einsteinsfool]

Christofides algorithm is O(n^3) because this is the time it takes to calculate minimum weight perfect matching. So people using your library might assume that this it's time complexity when in fact it's O(n!) (more precisely A000984). Might be a good idea to inform people about it.

[StupidHobbit]

Yeah, basically this whole package does not make any sense, because I can just use brute force and solve TSP with few lines of code with the same complexity.

[csaluigm]

Agree. This line starts to break the time complexity: bipartite_set = [set(i) for i in itertools.combinations(set(odd_vertices), int(len(odd_vertices)/2))]