Hi , congratulations on finishing successfully the exercise!
I found that the hardest part was to read the relevant section of the paper and make sense of it. Fortunately was of great help to answer any question.
My only comment about your code would be to be careful about the following:
jets.erase(jet_it);
// we have to move iterator back after removing the element
jet_it--;
since erase normally invalidates the iterator. The result is unspecified and yield to unexpected behavior (or crash) with some compilers.
Apart from that, great work! :-)
RE: Particle physics - exercise 1b solution