Hello.

I've just thought of a way to compute the linearization times (entry and exit) for a tree given by "the father of node $$$i$$$ is $$$p_i$$$ ($$$p_i \lt i$$$)" without the usual graph creation. This might improve the time of a submission (you no longer do push_backs) but I haven't tested. This is very niche (the number of problems where the tree is given in this way is small and those where you don't need the actual graph are even fewer) so feel free to ignore the blog.