Enqueue Using Linked List in DSA Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does 'enqueue' mean in the context of a queue data structure?

Enqueue means adding an element to the end (rear) of the queue.

beginner

Why is a linked list a good choice to implement a queue?

Because it allows efficient addition at the end and removal from the front without shifting elements.

beginner

In enqueue operation using a linked list, where is the new node added?

The new node is added at the rear (tail) of the linked list.

intermediate

What pointers are updated during enqueue in a linked list queue?

The rear pointer is updated to point to the new node; if the queue was empty, the front pointer also points to the new node.

beginner

What happens if you enqueue into an empty linked list queue?

Both front and rear pointers are set to the new node, as it is the only element.

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

A O(log n)

B O(n)

C O(n^2)

D O(1)

Enqueue adds a node at the rear in constant time because we keep a pointer to the rear.

When enqueuing a new node in a linked list queue, which pointer must be updated?

A Rear pointer, and front pointer if queue was empty

B Rear pointer only

C Both front and rear pointers always

D Front pointer only

Rear pointer always updates to new node; front pointer updates only if queue was empty.

What happens if you forget to update the rear pointer during enqueue?

A New nodes won't be linked properly, causing errors

B Queue will work normally

C Front pointer will point to wrong node

D Queue will become empty

Rear pointer must point to the last node; otherwise, new nodes are not linked correctly.

Which of these is NOT true about enqueue in linked list?

A It updates rear pointer

B It adds a node at the end

C It requires shifting all nodes

D It can handle empty queue

Linked list enqueue does not require shifting nodes; it just links new node at the end.

If the queue is empty, what should front and rear pointers be after enqueue?

A Both null

B Both point to the new node

C Rear points to new node, front is null

D Front points to new node, rear is null

When queue is empty, both front and rear point to the new node after enqueue.

Explain step-by-step how enqueue works in a linked list based queue.

Think about what pointers change and where the new node goes.

Describe how you would handle enqueue operation if the queue is initially empty.

Focus on initializing pointers for the first element.