Question

Questions

Submission Question 2: Stacks

Problem
Write a program that keeps track of where cars are located in a parking garage to estimate the time to retrieve a car when the garage is full.
This program will demonstrate the following:

How to create a list for use as a stack,

How to enter and change data in a stack.

Solving the Problem
Step 1
In Python, the stack data structure is actually implemented using the list data structure with a few additional functions. These functions come as part of the list structure, so it is really more about how to access the list to make it function like a stack rather than it actually being a different data structure from the list.
Step 2
To add cars to the stack, use the append method of the list structure like you would with any normal list.
Step 3
To find how long it will take to retrieve a certain car, you will have to use the pop() function of the list until you find the required vehicle in the garage stack and count the number of vehicles.
Step 4
Once the number of cars in front of the vehicle are found, the time taken to retrieve the car can be calculated based on the average time it takes to move a vehicle plus the time to retrieve the car.
Step 5
Finally, the estimated time to retrieve the vehicle can be output to the user to inform the car owner.
Documentation Guidelines:
Use good programming style (e.g., indentation for readability) and document each of your program parts with the following items (the items shown between the '<' and '>' angle brackets are only placeholders.  You should replace the placeholders and the comments between them with your specific information).  Your cover sheet should have some of the same information, but what follows should be at the top of each program's sheet of source code.  Some lines of code should have an explanation of what is to be accomplished, this will allow someone supporting your code years later to comprehend your purpose.  Be brief and to the point.  Start your design by writing comment lines of pseudocode.  Once that is complete, begin adding executable lines.  Finally run and test your program.

Answer 1

Note: The code has been implemented in Python 3. Please indent the code as shown in the screenshots.

Program screenshots:

Sample output:

Code to copy:

# Define the main() function.

def main():

    # Declare the required variables.

    stack_cars = []

    move_time = 1

    retrieve_time = 2

    # Start the loop to display the menu.

    while True:

        # Display the choices to the user.

        print("\n\t\t\t Car Stack Menu")

        print("\n1. Add a car")

        print("2. Retrieve a car")

        print("3. Show the car stack")

        print("4. Exit")

        # Prompt the user to enter the input.

        choice = input("\nEnter your choice: ")

        # Append the car in the stack if the choice is 1.

        if choice == '1':

            car = input("Enter the car name to add: ")

            stack_cars.append(car)

        

        # Remove the car from the stack if the choice is 2.

        elif choice == '2':

            car = input("Enter the car name to retrieve: ")

            # Display the error message if the car is not present.

            if car not in stack_cars:

                print(car + " is not present in the stack.")

            # Otherwise, compute the time to retrieve a car.

            else:

                # Declare a temp stack to move the cars.

                temp = []

                x = stack_cars.pop()

                count = 0

                # Start the loop to pop the cars from the stack

                # until the car to be retrieved is found.

                while x != car:

                    count += 1

                    # Store the car in the temp stack.

                    temp.append(x)

                    x = stack_cars.pop()

                # Start the loop to move the cars back in the

                # original stack.

                while len(temp) != 0:

                    stack_cars.append(temp.pop())

                # Compute and display the total time.

                total_time = move_time * count + retrieve_time

                print("Total time to retrieve", car, "=", total_time)

        

        # Display the stack if the choice is 3.

        elif choice == '3':

            print("Car stack =", stack_cars)

        # Return from the funtion if the choice is 4.

        elif choice == '4':

            print("Exiting from the program...")

            return

        

        # Display the message for invalid input.

        else:

            print("Error: Invalid choice!")

# Call the main() function.

if __name__ == "__main__":

    main()