Insert at Middle Specific Position in DSA Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does 'Insert at Middle Specific Position' mean in a linked list?

It means adding a new node at a given position inside the list, not at the start or end, but somewhere in the middle.

beginner

Which steps are needed to insert a node at a specific middle position in a singly linked list?

1. Traverse the list to the node just before the target position.<br>2. Create a new node.<br>3. Point the new node's next to the next node.<br>4. Update the previous node's next to the new node.

beginner

Why do we need to stop at the node before the target position when inserting in the middle?

Because we need to change the 'next' pointer of the previous node to point to the new node, so stopping one node before lets us do that safely.

beginner

What happens if the position to insert is 1 in a linked list?

Inserting at position 1 means adding at the start (head) of the list, so the new node becomes the new head.

intermediate

What should you do if the position to insert is greater than the length of the linked list?

You can either insert at the end or return an error/message saying the position is invalid, depending on the design choice.

When inserting a node at position 3 in a linked list, where should you stop traversing?

A At position 4 node

B At position 3 node

C At the head node

D At position 2 node

You stop at the node before the target position (position 2) to update its next pointer.

What pointer of the new node should be set during insertion?

A Its previous pointer to the head

B Its next pointer to null always

C Its next pointer to the node currently at the target position

D No pointers need to be set

The new node's next pointer should point to the node currently at the target position to maintain the list.

If you want to insert at the start of the list, what position number do you use?

A 1

B 0

C Length of list

D Any number

Position 1 means the start (head) of the list.

What happens if you try to insert at a position larger than the list length + 1?

A Invalid position, no insertion

B Insert at the start

C Overwrite existing node

D Insert at the end

Positions beyond list length + 1 are invalid for insertion.

Which data structure is commonly used to demonstrate insertion at a middle position?

A Stack

B Linked List

C Array

D Queue

Linked lists are commonly used to show insertion at specific positions.

Explain how to insert a new node at a specific middle position in a singly linked list.

Think about how pointers change when adding a node.

What are the edge cases to consider when inserting at a specific position in a linked list?

Consider positions at the start, beyond end, and empty list.