#include <stdio.h>
#include <stdlib.h>
 
// Define structure for a node
struct Node {
    int data;
    struct Node *next;
};
 
// Function to create a new node
struct Node* createNode(int data) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->next = NULL;
    return newNode;
}
 
// Function to display circular linked list
void display(struct Node *head) {
    struct Node *temp = head;
    if (head == NULL) {
        printf("\nList is empty.\n");
        return;
    }
 
    printf("\nCircular Linked List: ");
    do {
        printf("%d -> ", temp->data);
        temp = temp->next;
    } while (temp != head);
    printf("(back to head)\n");
}
 
// Function to insert node at beginning
struct Node* insertAtBeginning(struct Node *head, int data) {
    struct Node *newNode = createNode(data);
    struct Node *temp = head;
 
    if (head == NULL) {
        newNode->next = newNode; // circular link
        head = newNode;
        return head;
    }
 
    // Find last node
    while (temp->next != head)
        temp = temp->next;
 
    temp->next = newNode;
    newNode->next = head;
    head = newNode;
 
    printf("\nInserted %d at beginning.\n", data);
    return head;
}
 
// Function to insert node at end
struct Node* insertAtEnd(struct Node *head, int data) {
    struct Node *newNode = createNode(data);
    struct Node *temp = head;
 
    if (head == NULL) {
        newNode->next = newNode;
        head = newNode;
        return head;
    }
 
    while (temp->next != head)
        temp = temp->next;
 
    temp->next = newNode;
    newNode->next = head;
 
    printf("\nInserted %d at end.\n", data);
    return head;
}
 
// Function to insert node at specific position
struct Node* insertAtPosition(struct Node *head, int data, int pos) {
    struct Node *newNode = createNode(data);
    struct Node *temp = head;
    int i;
 
    if (pos == 1)
        return insertAtBeginning(head, data);
 
    for (i = 1; i < pos - 1 && temp->next != head; i++)
        temp = temp->next;
 
    if (temp->next == head && i < pos - 1) {
        printf("\nInvalid position!\n");
        free(newNode);
        return head;
    }
 
    newNode->next = temp->next;
    temp->next = newNode;
 
    printf("\nInserted %d at position %d.\n", data, pos);
    return head;
}
 
// Function to delete node from beginning
struct Node* deleteFromBeginning(struct Node *head) {
    struct Node *temp = head, *last;
 
    if (head == NULL) {
        printf("\nList is empty.\n");
        return NULL;
    }
 
    // Only one node
    if (head->next == head) {
        free(head);
        return NULL;
    }
 
    last = head;
    while (last->next != head)
        last = last->next;
 
    head = head->next;
    last->next = head;
    free(temp);
 
    printf("\nDeleted node from beginning.\n");
    return head;
}
 
// Function to delete node from end
struct Node* deleteFromEnd(struct Node *head) {
    struct Node *temp = head, *prev;
 
    if (head == NULL) {
        printf("\nList is empty.\n");
        return NULL;
    }
 
    // Only one node
    if (head->next == head) {
        free(head);
        return NULL;
    }
 
    while (temp->next != head) {
        prev = temp;
        temp = temp->next;
    }
 
    prev->next = head;
    free(temp);
 
    printf("\nDeleted node from end.\n");
    return head;
}
 
// Function to delete node from specific position
struct Node* deleteFromPosition(struct Node *head, int pos) {
    struct Node *temp = head, *prev;
    int i;
 
    if (head == NULL) {
        printf("\nList is empty.\n");
        return NULL;
    }
 
    if (pos == 1)
        return deleteFromBeginning(head);
 
    for (i = 1; i < pos && temp->next != head; i++) {
        prev = temp;
        temp = temp->next;
    }
 
    if (temp == head) {
        printf("\nInvalid position!\n");
        return head;
    }
 
    prev->next = temp->next;
    free(temp);
 
    printf("\nDeleted node at position %d.\n", pos);
    return head;
}
 
// Function to create list
struct Node* createList(int n) {
    struct Node *head = NULL;
    int data, i;
 
    for (i = 0; i < n; i++) {
        printf("Enter data for node %d: ", i + 1);
        scanf("%d", &data);
        head = insertAtEnd(head, data);
    }
    return head;
}
 
// Main function
int main() {
    struct Node *head = NULL;
    int choice, data, pos, n;
 
    printf("Enter number of initial nodes: ");
    scanf("%d", &n);
    head = createList(n);
 
    do {
        printf("\n========= CIRCULAR LINKED LIST MENU =========\n");
        printf("1. Display List\n");
        printf("2. Insert at Beginning\n");
        printf("3. Insert at End\n");
        printf("4. Insert at Position\n");
        printf("5. Delete from Beginning\n");
        printf("6. Delete from End\n");
        printf("7. Delete from Position\n");
        printf("8. Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);
 
        switch (choice) {
            case 1:
                display(head);
                break;
 
            case 2:
                printf("Enter data: ");
                scanf("%d", &data);
                head = insertAtBeginning(head, data);
                break;
 
            case 3:
                printf("Enter data: ");
                scanf("%d", &data);
                head = insertAtEnd(head, data);
                break;
 
            case 4:
                printf("Enter data: ");
                scanf("%d", &data);
                printf("Enter position: ");
                scanf("%d", &pos);
                head = insertAtPosition(head, data, pos);
                break;
 
            case 5:
                head = deleteFromBeginning(head);
                break;
 
            case 6:
                head = deleteFromEnd(head);
                break;
 
            case 7:
                printf("Enter position: ");
                scanf("%d", &pos);
                head = deleteFromPosition(head, pos);
                break;
 
            case 8:
                printf("\nExiting program.\n");
                break;
 
            default:
                printf("\nInvalid choice! Try again.\n");
        }
    } while (choice != 8);
 
    return 0;
}