# Python Data Structure and Algorithm Tutorial – Types of Linked List – Singly linked, doubly linked and circular

#### In this tutorial, you will learn different types of linked list. Also, you will find implementation of linked list in C.

There are three common types of Linked List.

It is the most common. Each node has data and a pointer to the next node.

Node is represented as:

``````struct node {
int data;
struct node *next;
}``````

A three-member singly linked list can be created as:

``````/* Initialize nodes */
struct node *one = NULL;
struct node *two = NULL;
struct node *three = NULL;

/* Allocate memory */
one = malloc(sizeof(struct node));
two = malloc(sizeof(struct node));
three = malloc(sizeof(struct node));

/* Assign data values */
one->data = 1;
two->data = 2;
three->data = 3;

/* Connect nodes */
one->next = two;
two->next = three;
three->next = NULL;

We add a pointer to the previous node in a doubly-linked list. Thus, we can go in either direction: forward or backward.

A node is represented as

``````struct node {
int data;
struct node *next;
struct node *prev;
}``````

A three-member doubly linked list can be created as

``````/* Initialize nodes */
struct node *one = NULL;
struct node *two = NULL;
struct node *three = NULL;

/* Allocate memory */
one = malloc(sizeof(struct node));
two = malloc(sizeof(struct node));
three = malloc(sizeof(struct node));

/* Assign data values */
one->data = 1;
two->data = 2;
three->data = 3;

/* Connect nodes */
one->next = two;
one->prev = NULL;

two->next = three;
two->prev = one;

three->next = NULL;
three->prev = two;

A circular linked list is a variation of a linked list in which the last element is linked to the first element. This forms a circular loop.

• for singly linked list, next pointer of last item points to the first item
• In the doubly linked list, prev pointer of the first item points to the last item as well.

A three-member circular singly linked list can be created as:

``````/* Initialize nodes */
struct node *one = NULL;
struct node *two = NULL;
struct node *three = NULL;

/* Allocate memory */
one = malloc(sizeof(struct node));
two = malloc(sizeof(struct node));
three = malloc(sizeof(struct node));

/* Assign data values */
one->data = 1;
two->data = 2;
three->data = 3;

/* Connect nodes */
one->next = two;
two->next = three;
three->next = one;

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