Highway Checkpoint Tolls

Question

Several toll checkpoints sit along a highway. Each time a car passes one, a log entry records its license plate and which checkpoint it was. A checkpoint's position is the number inside its name (letters are ignored), and driving between two checkpoints costs 10 per unit of distance between their positions. A trip from "K7" back to "K2", for instance, is charged |7 - 2| * 10 = 50. ...