Construct FSA from un-sorted list of arcs about k2 HOT 4 CLOSED

I'll add swap tomorrow.

For composition, seems we can number the states when iterating over the queue,
https://github.com/danpovey/k2/blob/master/k2/csrc/fsa_algo.cc#L332-L333
I have no idea about its necessity in determinization for now.

Anyway, if it would be added, I prefer to add the constructor as a function with output-arg.

from k2.

what if there is a cycle and the fsa cannot be topsorted?

Abort?

from k2.

Firstly, we should have the top-sorting optional: we may sometimes want to just reorder the final-state so it's the last one.

I'd suggest to exit the program with a printed message if the user requested top-sorting and it couldn't be top-sorted. But don't make that dependent on debug level.

from k2.

we should have the top-sorting optional: we may sometimes want to just reorder the final-state so it's the last one.

what if the graph is not connected? In this case, how to determine which state is the final state?

from k2.