It is the zombie apocalypse. Your car has limited fuel in it, and you will not be able to refill your tank once you run out. You are planning one final mission to gather supplies. You have identified 10 locations that you would like to visit, but you do not have enough fuel to visit all of the locations. Therefore, you have assigned each site a number of “survival points” that indicate how valuable the site’s resources are.
The diagram below shows your base, as well as the sites you would like to visit and their survival points.
The distances in miles among the locations are given below. (Each site name is abbreviated to its initial letter.) Your car has enough fuel to travel 20 miles. Your mission will begin at your base and, of course, must end there as well (otherwise the zombies will get you on your way back).
Plan a route that collects as many survival points as possible and can be completed using only your available fuel.
[Source: This book (yes, I wrote it) -- cited here for attribution, not self-promotion.]