Queues — Practice MCQs for CCAT

Correct Answer: B — FIFO

Queue follows FIFO - First In First Out principle.

Correct Answer: A — O(1)

Both enqueue and dequeue are O(1) operations.

Correct Answer: C — CPU Scheduling

CPU scheduling algorithms like Round Robin use queues.

Correct Answer: B — Queue

BFS uses queue to explore nodes level by level.

Correct Answer: B — rear wraps to front

In circular queue, rear wraps around to beginning if space available.

Correct Answer: B — Elements served by priority

In priority queue, elements are served based on priority, not arrival order.

Correct Answer: B — Double-ended queue

Deque is Double-ended queue allowing insertion/deletion at both ends.

Correct Answer: C — Expression evaluation

Expression evaluation uses stack, not queue.

Correct Answer: C — Both and space wastage

Array queue has overflow, underflow, and space wastage when elements are dequeued.

Correct Answer: C — Space wastage in linear queue

Circular queue reuses empty spaces at the front, solving space wastage.

Correct Answer: B — (rear + 1) % size == front

Queue is full when the next position of rear equals front: (rear + 1) % size == front.

Correct Answer: C — Stack

Two queues can be used to implement a stack by transferring elements.

Correct Answer: A — Insert at one end only

Input-restricted deque allows insertion at only one end but deletion at both ends.

Correct Answer: C — Insert at both ends, delete at one

Output-restricted deque allows insertion at both ends but deletion at only one end.

Correct Answer: C — Heap

Heap provides O(log n) insert and O(log n) extract-min/max for priority queue.

Correct Answer: B — Deque

Deque (double-ended queue) efficiently solves sliding window maximum in O(n).

Correct Answer: B — Empty

When front equals rear in most implementations, the queue is empty.

Correct Answer: B — Queue with hash map

Queue maintains order of characters while hash map tracks frequency.

Correct Answer: B — FIFO tracks access order

FIFO property helps track which element was accessed least recently.

Correct Answer: B — Circular queue

Circular queue models the circular arrangement of people in Josephus problem.