A Linked List is a sequential list of nodes (Objects) containing data and pointing to another (usually the next) node that also contains data.
Below is a list of terms we use when talking about linked lists and their corresponding definitions.
Head: is the first node in a linked list, it points to the first next node in the list.
Tail: is the last node in a linked list, it points to null.
Pointer: is the reference of the next node.
Node: is an object containing data and a pointer to another node.
Linked lists keep a reference of their Head and Tail nodes to make it easier to add and remove nodes.
1- Used in Lists, Queue, and Stack implementations.
2- For creating circular lists, modeling repeating event cycles.
3- For modeling real-world objects.
4- For hashtable separate chaining.
5- For implementing adjacency lists for graphs.
There are two main types of linked lists, singly and doubly.
Singly linked-lists hold a reference to the next node only, whether the doubly linked-lists hold two references one for the next node and another for the previous node.
Pros and Cons
While Singly linked-lists are easier to implement and use less memory, they don’t offer easy access to previous nodes.
On the other hand, doubly linked-lists can be traversed backward, yet they occupy 2 times space in memory.
Different operations in a Liked List have different time complexities. the table below shows the big O notation for the different possible operations in both singly and doubly linked-lists.