Delete by Value in Doubly Linked List in DSA Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a doubly linked list?

A doubly linked list is a chain of nodes where each node has three parts: data, a pointer to the next node, and a pointer to the previous node. This allows moving forward and backward through the list.

beginner

What does 'delete by value' mean in a doubly linked list?

It means finding the first node that contains a specific value and removing that node from the list, adjusting the pointers of neighboring nodes to keep the list connected.

intermediate

Which pointers need to be updated when deleting a node in a doubly linked list?

You need to update the 'next' pointer of the previous node and the 'prev' pointer of the next node to bypass the node being deleted.

intermediate

What happens if the node to delete is the head of the doubly linked list?

The head pointer must be updated to point to the next node, and if that node exists, its 'prev' pointer should be set to None.

beginner

What should you do if the value to delete is not found in the doubly linked list?

You should leave the list unchanged because there is no node with that value to delete.

In a doubly linked list, what does each node contain?

A Data, next pointer, previous pointer

B Data and next pointer only

C Data and previous pointer only

D Data only

Each node in a doubly linked list has data, a pointer to the next node, and a pointer to the previous node.

When deleting a node by value, what is the first step?

A Delete the last node

B Update the head pointer

C Set all pointers to None

D Find the node with the given value

You must first find the node that contains the value you want to delete.

If the node to delete is in the middle, which pointers are updated?

A No pointers need updating

B Only head pointer

C Previous node's next and next node's prev

D Only tail pointer

The previous node's next pointer and the next node's prev pointer are updated to bypass the deleted node.

What happens if the node to delete is the only node in the list?

A The node remains

B The list becomes empty (head is None)

C The next pointer is updated

D The previous pointer is updated

Deleting the only node means the list becomes empty, so the head pointer is set to None.

If the value to delete is not found, what should the function do?

A Do nothing and keep the list unchanged

B Delete the head node

C Delete the tail node

D Raise an error

If the value is not found, the list should remain unchanged.

Explain step-by-step how to delete a node by value in a doubly linked list.

Think about how pointers before and after the node change.

Describe how pointers change when deleting a middle node in a doubly linked list.

Focus on the two neighbors of the node.