I've made it obvious that they don't need to return after delivery, and also that it's looking for the shortest possible delivery time.

I've fixed this now by making it more clear.

Finally! Thank you both

Because after you delivered all of them, you don't have to return to the post, you finished.

Why (12 + 13 + 12) + (13 + 3 + 13) + (19 + 10) and not (12 + 13 + 12) + (13 + 3 + 13) + (19 + 10 + 19)

None of the inputs is the main road - what do you mean?

Which of the inputs is the main road?

I fixed your issue

Yes - that would do it.
Thanks for the quick response :)

It was my fault. I forgot to use assert_approx_equals()

Thank you for the feedback. I think it is ok now.

Python:

0.4815891979115 should equal 
0.48158919791148946