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

Recall & Review

beginner

What does the 'push' operation do in a linked list?

It adds a new node at the beginning (head) of the linked list, making it the new first element.

beginner

In a singly linked list, what pointer does the new node's 'next' field point to during a push?

It points to the current head node before the new node becomes the head.

intermediate

Why is push operation efficient in a linked list?

Because it only changes a few pointers and does not require shifting elements, so it runs in constant time O(1).

beginner

What happens to the head pointer after a push operation?

The head pointer is updated to point to the newly added node.

beginner

Show the sequence of nodes after pushing 3 nodes with values 10, 20, 30 in that order on an empty linked list.

After pushing 10: 10 -> null<br>After pushing 20: 20 -> 10 -> null<br>After pushing 30: 30 -> 20 -> 10 -> null

What is the time complexity of the push operation in a singly linked list?

A O(log n)

B O(1)

C O(n)

D O(n^2)

Push adds a node at the head and only changes pointers, so it runs in constant time O(1).

When pushing a new node, what should the new node's next pointer be set to?

A null

B itself

C tail node

D current head node

The new node's next pointer should point to the current head node before updating the head.

After pushing a node, which pointer changes in the linked list?

A Head pointer

B Tail pointer

C Both head and tail pointers

D No pointer changes

Only the head pointer changes to point to the new node after push.

If the linked list is empty, what does the new node's next pointer point to after push?

A tail node

B head node

C null

D itself

When the list is empty, the new node's next pointer points to null.

Which of these is NOT true about push operation in linked list?

A It requires shifting all nodes

B It inserts at the beginning

C It updates the head pointer

D It runs in constant time

Push does not require shifting nodes; it only changes pointers.

Explain step-by-step how to push a new node with value X onto a singly linked list.

Think about what happens to the head pointer and the new node's next pointer.

Describe how the linked list changes visually after pushing nodes with values 5, then 15, then 25.

Draw the list after each push to see the new head.