Your friends are planning an expedition to a small town deep in the Cana- dian north next winter break. They've researched all the travel options and have drawn up a directed graph whose nodes represent intermediate destinations and edges represent the roads between them In the course of this, they've also learned that extreme weather causes roads in this part of the world to become quite slow in the winter and may cause large travel delays. They've found an excellent travel Web site that can accurately predict how fast they'll be able to travel along th