implement ComputeForward/BackwardMaxWeights

[qindazhu]

• Implement ComputeForward(Backward)MaxWeights
• Add weights to FsaRender
• Changes in determinize.cc are just fixing some style issues.

[qindazhu]

ComputeForwardMaxWeights:
https://github.com/danpovey/k2/blob/dbba25b59b1da8e8a671507ea737fbb98df9cbf3/k2/csrc/weights_test.cc#L53-L54

ComputeBackwardMaxWeights:
https://github.com/danpovey/k2/blob/dbba25b59b1da8e8a671507ea737fbb98df9cbf3/k2/csrc/weights_test.cc#L65-L66

[qindazhu]

Cancelled style check as it took so long time to install cppcheck..

[qindazhu]

Updated, Ready to merge.

[csukuangfj]

cppcheck can be disabled by commenting out the following code

https://github.com/danpovey/k2/blob/9bb1b26e9b3630a62f45f245ae96918779511f68/.github/workflows/style_check.yml#L47-L56

and
https://github.com/danpovey/k2/blob/9bb1b26e9b3630a62f45f245ae96918779511f68/.github/workflows/style_check.yml#L71-L74

[qindazhu]

cppcheck can be disabled by commenting out the following code

mm..OK. BTW, I'm fine with removing cppcheck if you think clang-tidy is good enough.

[qindazhu]

Ready to merge. Please ignore issues from determinize.cc for now

[danpovey]

Cool, I'll wait for @csukuangfj to merge.

[danpovey]

BTW, I am considering whether at some point it might make sense to relax the constraint that final_state be numbered last (except for top-sorted FSAs). It might turn out that removing that constraint will simplify code. Just something to keep in mind as you code stuff. We could put this into class Fsa for now, maybe, to make any future change less disruptive.

  int32_t FinalState() const {
    // It's not valid to call this if the FSA is empty.                                                                                                                            
    CHECK(!arc_indexes.empty());
    return arc_indexes.size() - 2;
  }

[qindazhu]

Added! As wee have gotten final_state with int32_t final_state = fsa.NumState() - 1 before, we may need to update those code one by one. ( but for now I believe numbering final state as the last one if convenient)

[csukuangfj]

+2 merging.