Find a map of the routes of a major U. S. airline. Such maps are usually printed at the back of in-flight magazines. You could also search the Internet for one. The map is a graph like the one in Figure 28-6. Consider the following pairs of cities:
Providence (RI) and San Diego (CA)
Albany (NY) and Phoenix (AZ)
Boston (MA) and Baltimore (MD)
Dallas (TX) and Detroit (MI)
Charlotte (NC) and Chicago (IL)
Portland (ME) and Portland (OR)
a. Which pairs of cities in this list have edges (nonstop flights) between them?
b. Which pairs are not connected by any path?
c. For each of the remaining pairs, find the path with the fewest edges.