What types of linked lists exist?

There are several types of linked lists, and they differ in how the nodes (elements) are connected.

The main idea is that every node has data and references (pointers) to other nodes.

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#1. Singly Linked List

Each node stores:

• data,
• a reference to the next element (next).

• Movement is possible only forward.
• To delete an element, you need to know the previous node.
• The end of the list (tail) has a None reference.

Pros: simple implementation, memory savings. Cons: you cannot move backward, access by index is slow (O(n)).

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#2. Doubly Linked List

Each node stores:

• data,
• a reference to the next element (next),
• a reference to the previous one (prev).

• You can move in both directions.
• Easier to delete and insert elements.

Pros: flexible, fast insertions and deletions. Cons: requires more memory (two references instead of one).

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#3. Circular Linked List

The last element (tail) does not point to None, but to the first element (head), forming a ring.

• Can be singly linked or doubly linked.
• Convenient for circular structures (for example, circular queues).

Pros: you can traverse the list endlessly in a loop. Cons: requires care - it is easy to end up in an infinite loop.

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#4. Multi-linked list (or skip list)

Each node stores several references to different "levels" of the list. Used to speed up search (an example is the Skip List data structure).

Pros: search is faster than in an ordinary list (O(log n) on average). Cons: implementation is more complex.

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#Summary:

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Conclusion:

All linked lists work on the same idea - a chain of nodes with references, but different types give a different balance between speed, memory, and flexibility.