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DoublyCircularLinkedList.c
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DoublyCircularLinkedList.c
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#include <stdio.h>
#include <stdlib.h>
typedef struct node {
int data;
struct node *prev, *next;
} Node;
typedef struct list {
Node* head;
int no_of_elements;
} List;
List* init_list();
void display(List*);
void destroy_list(List*);
void insert_front(List*, int);
void insert_end(List*, int);
void insert_pos(List*, int, int);
void delete_front(List*);
void delete_end(List*);
void delete_pos(List*, int);
void delete_val(List*, int);
int main() {
List *list = NULL;
list = init_list();
int ch;
int data;
while (1) {
printf("\n\nMAIN MENU\n\n");
printf("1. Insert element to front\n");
printf("2. Insert element to end\n");
printf("3. Insert into any position\n");
printf("4. Delete element at front\n");
printf("5. Delete element at end\n");
printf("6. Delete element from any position\n");
printf("7. Delete first occurance of value\n");
printf("8. Display\n");
printf("9. Exit\n");
printf("\nYour choice: ");
scanf("%d", &ch);
switch (ch) {
case 1: {
// Front insert
printf("Enter number: ");
scanf("%d", &data);
insert_front(list, data);
display(list);
break;
}
case 2: {
// End insert
printf("Enter number: ");
scanf("%d", &data);
insert_end(list, data);
display(list);
break;
}
case 3: {
// Insert pos
int pos, val;
printf("Enter position (1-based index): ");
scanf("%d", &pos);
printf("Enter value: ");
scanf("%d", &val);
insert_pos(list, pos, val);
display(list);
break;
}
case 4: {
// Delete front
delete_front(list);
display(list);
break;
}
case 5: {
// Delete end
delete_end(list);
display(list);
break;
}
case 6: {
// Delete pos
int pos;
printf("Enter position (1-based index): ");
scanf("%d", &pos);
delete_pos(list, pos);
display(list);
break;
}
case 7: {
// Delete val
int val;
printf("Enter value: ");
scanf("%d", &val);
delete_val(list, val);
display(list);
break;
}
case 8: {
// Display
display(list);
break;
}
case 9: {
// Exit
destroy_list(list);
return 0;
}
default: {
printf("Invalid input\n");
continue;
}
}
}
destroy_list(list);
return 0;
}
List* init_list() {
List *list = (List*) malloc(sizeof(List));
list->head = NULL;
list->no_of_elements = 0;
return list;
}
void destroy_list(List *list) {
Node *temp = list->head, *to_delete = NULL;
if (temp == NULL) {
return;
}
do {
to_delete = temp;
if (to_delete != NULL) {
free(to_delete);
}
temp = temp->next;
} while (temp != list->head);
if (list != NULL) {
free(list);
}
}
void insert_front(List *list, int val) {
Node *traverse = list->head;
Node* new_node = NULL;
new_node = (Node*) malloc(sizeof(Node));
new_node->data = val;
++list->no_of_elements;
// If not first node
if (traverse != NULL) {
new_node->next = traverse;
// Find last node
traverse = traverse->prev;
new_node->prev = traverse;
traverse->next = new_node;
list->head->prev = new_node;
}
else {
new_node->next = new_node;
new_node->prev = new_node;
}
list->head = new_node;
}
void insert_end(List *list, int val) {
// Same as front insert; do not change list head
Node *traverse = list->head;
Node* new_node = NULL;
new_node = (Node*) malloc(sizeof(Node));
new_node->data = val;
++list->no_of_elements;
// If not first node
if (traverse != NULL) {
new_node->next = traverse;
// Find last node
traverse = traverse->prev;
new_node->prev = traverse;
traverse->next = new_node;
list->head->prev = new_node;
}
else {
new_node->next = new_node;
new_node->prev = new_node;
list->head = new_node;
}
}
void insert_pos(List *list, int pos, int val) {
Node *traverse = list->head;
Node* new_node = NULL;
// List is empty
if (traverse == NULL) {
new_node = (Node*) malloc(sizeof(Node));
new_node->data = val;
new_node->next = new_node;
new_node->prev = new_node;
list->head = new_node;
++list->no_of_elements;
return;
}
if (pos == 0) {
insert_front(list, val);
}
int counter = 1;
do {
// Position found, insert after
if (pos == counter) {
new_node = (Node*) malloc(sizeof(Node));
new_node->data = val;
// Set next and next's prev
new_node->next = traverse->next;
(traverse->next)->prev = new_node;
// Set prev and prev's next
traverse->next = new_node;
new_node->prev = traverse;
++list->no_of_elements;
return;
}
traverse = traverse->next;
++counter;
} while (traverse != list->head);
}
void delete_front(List *list) {
if (list->head == NULL) {
return;
}
Node* to_del = list->head;
if (list->head->next != list->head) {
// Correct prev and next links
list->head->next->prev = list->head->prev;
list->head->prev->next = list->head->next;
list->head = list->head->next;
}
// Only one element
else {
list->head = NULL;
}
free(to_del);
--list->no_of_elements;
}
void delete_end(List *list) {
if (list->head == NULL) {
return;
}
Node *to_del = list->head->prev;
// More than one element
if (list->head != list->head->prev) {
// Correct prev and next links
to_del->prev->next = list->head;
list->head->prev = to_del->prev;
}
// Only one element
else {
list->head = NULL;
}
free(to_del);
--list->no_of_elements;
}
void delete_pos(List *list, int pos) {
// List is empty
if (list->head == NULL) {
return;
}
Node *traverse = list->head;
Node* to_del = NULL;
int counter = 1;
do {
// Position found, value
if (pos == counter) {
to_del = traverse;
if (to_del == list->head) {
list->head = list->head->next;
}
// If not only node
if (traverse != traverse->next) {
to_del->prev->next = to_del->next;
to_del->next->prev = to_del->prev;
}
// Only node
else {
list->head = NULL;
}
free(to_del);
--list->no_of_elements;
return;
}
traverse = traverse->next;
++counter;
} while (traverse != list->head);
}
void delete_val(List *list, int val) {
// List is empty
if (list->head == NULL) {
return;
}
Node *traverse = list->head;
Node* to_del = NULL;
do {
// Value found, delete
if (val == traverse->data) {
to_del = traverse;
if (to_del == list->head) {
list->head = list->head->next;
}
// If not only node
if (traverse != traverse->next) {
to_del->prev->next = to_del->next;
to_del->next->prev = to_del->prev;
}
// Only node
else {
list->head = NULL;
}
free(to_del);
--list->no_of_elements;
return;
}
traverse = traverse->next;
} while (traverse != list->head);
}
void display(List *list) {
Node *traverse = list->head;
if (traverse == NULL) {
printf("END\n");
return;
}
do {
printf("%d->", traverse->data);
traverse = traverse->next;
} while (traverse != list->head);
printf("END\n");
}