Enqueue Operation in DSA C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the enqueue operation do in a queue?

It adds a new element to the end (rear) of the queue, following the First-In-First-Out (FIFO) principle.

intermediate

In a queue implemented using an array, what happens when the rear index reaches the maximum size?

The queue is considered full, and no more elements can be added unless some are dequeued or the queue is reset (circular queue can help here).

beginner

What is the time complexity of the enqueue operation in a queue?

The time complexity is O(1) because adding an element at the rear is a constant-time operation.

intermediate

Show the basic steps of enqueue operation in a linked list based queue.

1. Create a new node with the data.<br>2. Set the next pointer of the current rear node to the new node.<br>3. Update the rear pointer to the new node.<br>4. If the queue was empty, set front pointer to the new node too.

beginner

What error condition should be checked before enqueueing in a fixed-size queue?

Check if the queue is full (rear index is at max size - 1). If full, enqueue should not proceed to avoid overflow.

What does the enqueue operation add to a queue?

A Removes an element from the front

B An element at the front

C An element at the rear

D Removes an element from the rear

Enqueue adds an element at the rear of the queue.

What happens if you try to enqueue in a full fixed-size queue?

A Queue overflow error occurs

B The element is added successfully

C The front pointer moves forward

D The queue becomes empty

Trying to enqueue in a full queue causes overflow error.

In a linked list queue, what pointer is updated during enqueue?

A Front pointer

B Both front and rear pointers always

C Neither pointer

D Rear pointer

The rear pointer is updated to the new node during enqueue.

What is the time complexity of enqueue operation in a queue?

A O(1)

B O(log n)

C O(n^2)

D O(n)

Enqueue is a constant time operation, O(1).

Which data structure principle does enqueue follow?

A Last-In-First-Out (LIFO)

B First-In-First-Out (FIFO)

C Random Access

D Priority based

Queue follows FIFO, so enqueue adds at the rear.

Explain the steps involved in the enqueue operation for a queue implemented using an array.

Think about how the rear index changes and what to do if the queue is empty or full.

Describe how enqueue works in a linked list based queue and how it differs from array implementation.

Focus on pointers and dynamic memory.