Implement an expanded version of the HPAir problem. In addition to the "from') a...

Implement an expanded version of the HPAir problem. In addition to the "from') and "to" cities, each line of input contains a flight number (an integer) and the cost of the flight (an integer). Modify the HPAir program so that it will produce a complete itinerary for each request, including the flight number of each flight, the cost of each flight, and the total cost of the trip. For example, the input files could appear as

For this input, the program should produce the following output:

When the nonrecursive isPath method finds a sequence of flights from the origin city to the destination city, its stack contains the corresponding path of cities. The stumbling block to reporting this path is that the cities appear in the stack in reverse order; that is, the destination city is at the top of the stack and the origin city is at the bottom. For example, if you use the program to find a path from city P to city Z in Figure 7-10, the final contents of the stack will be P-W-Y-Z, with Z on top. You want to display the origin city P first, but it is at the bottom of the stack. If you restrict yourself to the stack operations, the only way that you can write the path in its correct order is first to reverse the stack by popping it onto a temporary stack and then to write the cities as you pop them off the temporary stack. Note that this approaCh requires that you process each city on the path twice.

Evidently a stack is not the appropriate ADT for the problem of writing the path of cities in the correct order; the appropriate ADT is a traversable stack. In addition to the standard stack operations, isEmpty, push, pop, and peek, a traversable stack includes the operation traverse. This operation begins at one end of the stack and visits each item in the stack until it reaches the other end of the stack. For this project, you want traverse to begin at the bottom of the stack and move toward the top.