Exercise 06-17:
Modify the program to work with two lines. To make your job easier, consider command S for serving line 1 and T for servicing line 2. The same for the arrival of customers: A for line 1 and B for line 2.
Answer:
##############################################################################
# Python From Scratch
# Author: Nilo Ney Coutinho Menezes
# Editora Novatec (c) 2010-2025 - LogiKraft 2025
# Site: https://pythonfromscratch.com
# ISBN: 978-85-7522-949-1 (Paperback), 978-85-7522-950-7 (hardcover), 978-85-7522-951-4 (ebook)
#
# File: chapter 06/exercise-06-06.py.py
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last = 0
queue1 = []
queue2 = []
while True:
print(
f"\nThere are {len(queue1)} customers in queue 1 and {len(queue2)} in queue 2."
)
print("Current queue 1:", queue1)
print("Current queue 2:", queue2)
print("Enter A to add a customer to the end of queue 1 (or B for queue 2),")
print("or S to serve queue 1 (or T for queue 2)")
print("X to exit.")
operation = input("Operation (A, B, S, T or X):")
x = 0
exit = False
while x < len(operation):
# Here we'll use queue as a reference to queue 1
# or queue 2, depending on the operation.
if operation[x] == "A" or operation[x] == "S":
queue = queue1
else:
queue = queue2
if operation[x] == "S" or operation[x] == "T":
if len(queue) > 0:
served = queue.pop(0)
print(f"Customer {served} served")
else:
print("Empty queue! No one to serve.")
elif operation[x] == "A" or operation[x] == "B":
last += 1 # Increments the new customer's ticket
queue.append(last)
elif operation[x] == "X":
exit = True
break
else:
print(
f"Invalid operation: {operation[x]} at position {x}! Enter only A, B, S, T or X!"
)
x += 1
if exit:
break