Using Decomposition & Abstraction (Edexcel GCSE Computer Science)

def calculate_pizza_price(size):

# -----------------------------------------------------------------------
# This function takes the pizza size as input and returns the base price

# -----------------------------------------------------------------------

base_prices = {"small": 5, "medium": 10, "large": 20}

return base_prices[size]

def get_user_choice(options):

# -----------------------------------------------------------------------

# This function displays options and gets valid user input from the provided list

# -----------------------------------------------------------------------

while True:

choice = input("Choose from "+", ".join(options)+": ").lower()

if choice in options:

return choice

else:

print("Invalid choice. Please try again.")

def calculate_topping_cost(toppings, topping_prices):

# -----------------------------------------------------------------------

# This function calculates the total cost of selected toppings

# -----------------------------------------------------------------------

total_cost = 0

for topping in toppings:

total_cost = total_cost + topping_prices[topping]

return total_cost

def apply_discount(total_cost):

# -----------------------------------------------------------------------

# This function applies a 10% discount if the total cost exceeds £20

# -----------------------------------------------------------------------

if total_cost > 20:

discount = total_cost * 0.1

total_cost = total_cost - discount

return total_cost

def main():

# -----------------------------------------------------------------------

# This function coordinates the program flow and calls other functions

# -----------------------------------------------------------------------

pizza_size = get_user_choice(["small", "medium", "large"])

base_price = calculate_pizza_price(pizza_size)

toppings_available = ["pepperoni", "mushrooms", "onions"]

toppings = []

while True:

add_topping = input("Add a topping (y/n)?").lower()

if add_topping == 'n':

break

else:

topping = get_user_choice(toppings_available)

toppings.append(topping)

topping_cost = calculate_topping_cost(toppings, {"pepperoni": 1, "mushrooms": 0.5, "onions": 0.75})

total_cost = base_price + topping_cost

total_cost = apply_discount(total_cost)

print("Your total pizza cost is: £",total_cost)

# -----------------------------------------------------------------------

# Main program starts here

# -----------------------------------------------------------------------

main()