Doubly linked lists are often seen as better than singly linked lists for a few important reasons related to how they work. Let’s break down their advantages in simpler terms:

How They Are Structured:

• Node Composition:
  A node in a doubly linked list has three parts:
  1. A place to store data.
  2. A pointer to the next node.
  3. A pointer to the previous node.
  In a singly linked list, each node only has two parts:
  1. A place to store data.
  2. A pointer to the next node.

Why Doubly Linked Lists Are Better:

1. Moving Both Ways:

   • You can go forward and backward in a doubly linked list. This makes it easier to do things like go back to previous nodes or run certain algorithms. In a singly linked list, you can only move in one direction—forward.

2. Easier Deletion:

   • When you want to delete a node in a doubly linked list, it’s quicker. In a singly linked list, you need to know the previous node to unlink the one you want to remove. But in a doubly linked list, each node knows its previous node, making deletion faster and easier.

3. Flexible Insertion:

   • Adding new nodes can also happen more smoothly. With pointers that go both ways, it’s simpler to insert new nodes before or after an existing node.

4. Support for Complex Structures:

   • Doubly linked lists can help create more complicated data structures, like deques (which let you add or remove items from both ends) and certain tree structures. They allow for easy insertions and deletions from either end.

How They Perform:

• Time Complexity:
  • Both types of linked lists usually take the same amount of time for basic actions:
    • Accessing a node: $O(n)$ (this is pretty slow and depends on the number of nodes)
    • Inserting a node: $O(1)$ (if you already know where to insert)
    • Deleting a node: $O(1)$ (if you know which node to delete)
  • However, doubly linked lists are especially better when you often need to insert or delete nodes at different spots.

In short, while singly linked lists are easier to work with and use less space, doubly linked lists offer more flexibility and usefulness. They are great for more complex tasks and situations in computer science where you need to move, add, or remove items often.