Thanks for the guide.
std::get<0>(max(x,1,false)) seems to work.
There is another with torch.max(x1,1)[1].data
In this case, is
std::get<1>(max(x1,1,false)) equivalent to  torch.max(x1,1)[1].data
because std::get<1>(max(x1,1,false)).data() is also valid.
Just to confirm