OK so there is no shop
I thought about having a distinct start and end point, but it seems this could actually make it easier. I your scripts knows where to start then that job is done, if however it has to find the best starting point it make it just that tiny bit more interesting.
Im aware that 'shortest route' algorithms are by far one of the most common and many are available to use, but its not about what algorithm you use, it how you code it!!
Anyway who said anything about a shop? the Pizza Dude cooks the pizzas right there on his bike (with a blow torch) - and phones his buddy to drop him off (at the starting point) and pick him up when he's done, lol ;-)