Queue

Topics in this chapter

• Queue Principles and Operations
• Python List Queue Implementation
• Array and Circular Queue Mechanics
• Linked Queue Pointers
• Queue Applications

Cheat sheet

Practice questions

1. Question 1Q-9FDB4F

   Which principle is followed by a queue?

   1. A.LIFO (Last In, First Out)
   2. B.FIFO (First In, First Out)
   3. C.Random access only
   4. D.Priority-based access only
   See the answer and solution
2. Question 2Q-525CA3

   What will be printed by the following Python code? q = []; q.append(10); q.append(20); q.pop(0); q.append(30); print(q[0], q.pop(0))

   1. A.10 10
   2. B.20 20
   3. C.20 30
   4. D.30 30
   See the answer and solution
3. Question 3Q-01C3CF

   Explain how enqueue and dequeue operations can be implemented for a queue using a Python list. Also state what should happen when dequeue is attempted on an empty queue.

   See the answer and solution
4. Question 4Q-AF4DF7

   A queue currently contains [12, 18, 25], where 12 is at the front. After one dequeue, one enqueue of 31, and one more dequeue, which list represents the queue from front to rear?

   1. A.[12, 18, 25, 31]
   2. B.[18, 25, 31]
   3. C.[25, 31]
   4. D.[31, 25]
   See the answer and solution
5. Question 5Q-3F67AE

   What will be the output of the following Python code? q = [4, 8] def remove_item(q): if len(q) == 0: return "Underflow" return q.pop(0) print(remove_item(q), remove_item(q), remove_item(q))

   1. A.4 8 Underflow
   2. B.8 4 Underflow
   3. C.4 8 0
   4. D.Underflow 4 8
   See the answer and solution