1. Shortest-path modeling Assume you have a model of a weighted connected graph made of balls (representing the vertices) connected by strings of appropriate lengths (representing the edges).
a. Describe how you can solve the single-pair shortest-path problem with this model.
b. Describe how you can solve the single-source shortest-paths problem with this model.
2. Revisit the exercise from Section 1.3 about determining the best route for a subway passenger to take from one designated station to another in a welldeveloped subway system like those in Washington, DC, or London, UK. Write a program for this task.