$3.[$Cyberjunk$]$: The new car released by the multi$-$billionaire Elon Tusk's company, named Cyberjunk, has shown great promise and has become extremely popular on Tooth$-$Social. This marvelous piece of technology can drive many miles on a single charge and tow multiple cars simultaneously! However, the price of the car is a bit too steep for a university professor's salary, so I need your help to optimize my travel plan to Los Angeles at the end of the semester.

Suppose that on the route from Iowa City to Los Angeles, there are charging stations located at $\backslash ($ x$\_\{1\}$