Doubly Circular Linked List

A doubly circular linked list is a type of linked list where each node has both a "next" and a "previous" pointer, allowing for traversal in both directions. Additionally, the last node in the list points back to the first node, forming a circle.

#include <stdio.h>

#include <stdlib.h>

struct Node {

int data;

struct Node* next;

struct Node* prev;

};

struct DoublyCircularLinkedList {

struct Node* head;

int count;

};

struct Node* create_node(int data) {

struct Node* node = (struct Node*)malloc(sizeof(struct Node));

node->data = data;

node->next = NULL;

node->prev = NULL;

return node;

}

struct DoublyCircularLinkedList* create_list() {

struct DoublyCircularLinkedList* list = (struct DoublyCircularLinkedList*)malloc(sizeof(struct DoublyCircularLinkedList));

list->head = NULL;

list->count = 0;

return list;

}

void append(struct DoublyCircularLinkedList* list, int data) {

struct Node* node = create_node(data);

if (list->head == NULL) {

list->head = node;

node->next = node; // make the node point to itself

node->prev = node;

} else {

node->next = list->head;

node->prev = list->head->prev;

list->head->prev->next = node;

list->head->prev = node;

}

list->count++;

}

int remove_node(struct DoublyCircularLinkedList* list, int data) {

if (list->head == NULL) {

return 0;

}

struct Node* current = list->head;

do {

if (current->data == data) {

if (current == list->head) {

list->head = current->next;

}

current->prev->next = current->next;

current->next->prev = current->prev;

free(current);

list->count--;

return 1;

}

current = current->next;

} while (current != list->head);

return 0;

}

void print_list(struct DoublyCircularLinkedList* list) {

if (list->head == NULL) {

return;

}

struct Node* current = list->head;

do {

printf("%d ", current->data);

current = current->next;

} while (current != list->head);

printf("\n");

}

int main() {

struct DoublyCircularLinkedList* list = create_list();

append(list, 1);

append(list, 2);

append(list, 3);

print_list(list); // output: 1 2 3

remove_node(list, 2);

print_list(list); // output: 1 3

return 0;

}