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 traversal in both directions.
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beginner
What steps are needed to insert a new node at the beginning of a doubly linked list?
1. Create a new node.<br>2. Set new node's next pointer to current head.<br>3. Set new node's previous pointer to NULL.<br>4. If list is not empty, set current head's previous pointer to new node.<br>5. Update head to new node.
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beginner
In C, what struct members are needed for a doubly linked list node?
A struct for a doubly linked list node typically has:<br> - an integer data field<br> - a pointer to the next node<br> - a pointer to the previous node
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beginner
Why do we set the previous pointer of the new node to NULL when inserting at the beginning?
Because the new node will be the first node, it has no previous node, so its previous pointer must be NULL to mark the start of the list.
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beginner
What happens if the doubly linked list is empty when inserting at the beginning?
If the list is empty, the new node becomes the only node. Its next and previous pointers are NULL, and the head points to this new node.
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What pointer of the new node should point to the current head when inserting at the beginning?
✗ Incorrect
The new node's next pointer should point to the current head node.
When inserting at the beginning, what should the previous pointer of the new node be set to?
✗ Incorrect
The previous pointer of the new node is NULL because it becomes the first node.
If the list is not empty, what pointer of the old head node must be updated after insertion?
✗ Incorrect
The old head node's previous pointer must point to the new node.
What is the final step after inserting a new node at the beginning?
✗ Incorrect
The head pointer must be updated to point to the new node.
Which of these is NOT a part of a doubly linked list node?
✗ Incorrect
Nodes do not have a pointer to the head; only next and previous pointers.
Explain how to insert a new node at the beginning of a doubly linked list in C.
Think about pointers and updating head.
You got /5 concepts.
Describe the structure of a doubly linked list node and why each pointer is important.
Imagine walking forward and backward through a chain.
You got /5 concepts.