简单算法

def discount(size, count):
    price_8oz = 1.20
    price_12oz = 1.75
    price_12oz_discount = 1.35
    if size == 8:
        return price_8oz * count
    elif size == 12:
        if count <= 4:
            return price_12oz * count
        elif count > 4:
            # divmod() divides one number by another and returns both the number of times
            #     the second number fits into the first, but also the remainder.
            # Here we calculate how many times five goes into the customer order 
            #     and how many extra cups are left over.
            fivecount, remainder = divmod(count, 5)
            return price_12oz_discount * fivecount * 5 + 1.75 * remainder
# Here we test the code to make sure that it works across several iterations of five counts
#    with 12 ounce cups.
for count in range(2, 12):
    print('count:', count, 'cost:', discount(12, count))