Linked list

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Linked list

A linked list is an abstract data type that stores data in nodes, each containing a value and a reference to the next node in the list. Linked lists provide efficient insertion or deletion of elements at any point in the list, but slower random access to data.

What does Linked list mean?

A linked list is a linear data structure that stores data elements in a series of linked nodes. Each node contains a data item and a reference (or link) to the next node in the list. The last node in the list has a null reference, indicating that it is the end of the list.

Unlike arrays, Which Store elements contiguously in memory, linked lists allow for dynamic memory allocation, meaning that nodes can be added or removed without affecting the rest of the list. The First node in the list is referred to as the head, While the last node is referred to as the tail.

Linked lists are classified into two main types: singly linked lists and doubly linked lists. In a singly linked list, each node contains a reference to the next node only, while in a doubly linked list, each node contains references to both the previous and next nodes. Doubly linked lists allow for faster navigation and deletion operations compared to singly linked lists.

Applications

Linked lists are widely used in a variety of computing applications, including:

  • Implementing stacks and queues
  • Representing graphs and trees
  • Maintaining lists of items with variable lengths
  • Dynamic memory management
  • Sparse matrices
  • Object caching
  • Undo/redo operations in text editors
  • File systems

Linked lists are particularly useful in situations where frequent insertions and deletions are required, as they do not suffer from the performance penalties associated with array resizing.

History

The concept of linked lists dates back to the early days of computer science. In 1955, Allen Newell, Cliff Shaw, and Herbert Simon introduced linked lists as a data structure in their Information Processing Language (IPL). Linked lists gained widespread recognition in the late 1960s and early 1970s as a key data structure in Lisp and other symbolic programming languages.

Throughout the evolution of computing, linked lists have remained a fundamental data structure for many applications. They offer efficient memory management, flexibility in adding and removing elements, and the ability to represent complex data relationships. Modern programming languages and applications continue to heavily rely on linked lists for a wide range of tasks.