Linked list
In computer science, a linked list is a data structure consisting of a group of nodes which together represent a sequence.
Contents
Description
Under the simplest form, each node is composed of data and a reference (in other words, a link) to the next node in the sequence; more complex variants add additional links.
This structure allows for efficient insertion or removal of elements from any position in the sequence.
Linked lists are among the simplest and most common data structures.
Integer value and link to next node
A linked list whose nodes contain two fields: an integer value and a link to the next node.
The last node is linked to a terminator used to signify the end of the list.
Basis for other abstract data types
They can be used to implement several other common abstract data types, including:
- Lists (the abstract data type)
- Stacks
- Queues
- Associative arrays
- S-expressions
It is not uncommon to implement these other data structures directly without using a list as the basis of implementation.
Advantages
The principal benefit of a linked list over a conventional array is that the list elements can easily be inserted or removed without reallocation or reorganization of the entire structure because the data items need not be stored contiguously in memory or on disk, while an array has to be declared in the source code, before compiling and running the program. Linked lists allow insertion and removal of nodes at any point in the list, and can do so with a constant number of operations if the link previous to the link being added or removed is maintained during list traversal.
Disadvantages
On the other hand, simple linked lists by themselves do not allow random access to the data, or any form of efficient indexing. Thus, many basic operations — such as obtaining the last node of the list (assuming that the last node is not maintained as separate node reference in the list structure), or finding a node that contains a given datum, or locating the place where a new node should be inserted — may require sequential scanning of most or all of the list elements.
See also
External links
- Linked list @ Wikipedia
