#include <iostream>
using namespace std;
class CircularLinkedList {
private:
struct Node {
int data;
Node* next;
};
Node* head;
public:
CircularLinkedList() {
head = NULL;
}
void insertBegin(int value) {
Node* newNode = new Node();
newNode->data = value;
if (head == NULL) {
newNode->next = newNode;
} else {
Node* tail = head;
while (tail->next != head) {
tail = tail->next;
}
tail->next = newNode;
newNode->next = head;
}
head = newNode;
}
void insertEnd(int value) {
Node* newNode = new Node();
newNode->data = value;
if (head == NULL) {
newNode->next = newNode;
head = newNode;
} else {
Node* tail = head;
while (tail->next != head) {
tail = tail->next;
}
tail->next = newNode;
newNode->next = head;
}
}
void insertAfter(int key, int value) {
if (head == NULL) {
return;
}
Node* current = head;
do {
if (current->data == key) {
Node* newNode = new Node();
newNode->data = value;
newNode->next = current->next;
current->next = newNode;
if (current == head && current->next == head) {
head = newNode;
}
return;
}
current = current->next;
} while (current != head);
}
void insertByPosition(int position, int value) {
if (position <= 0) {
insertBegin(value);
} else {
Node* newNode = new Node();
newNode->data = value;
Node* current = head;
for (int i = 0; i < position - 1; i++) {
current = current->next;
if (current == head) {
return;
}
}
newNode->next = current->next;
current->next = newNode;
if (current == head && newNode->next == head) {
head = newNode;
}
}
}
void deleteBegin() {
if (head == NULL) {
return;
}
if (head->next == head) {
delete head;
head = NULL;
return;
}
Node* tail = head;
while (tail->next != head) {
tail = tail->next;
}
Node* temp = head;
head = head->next;
tail->next = head;
delete temp;
}
void deleteEnd() {
if (head == NULL) {
return;
}
if (head->next == head) {
delete head;
head = NULL;
return;
}
Node* current = head;
Node* prev = NULL;
while (current->next != head) {
prev = current;
current = current->next;
}
prev->next = head;
delete current;
}
void deleteAfter(int key) {
if (head == NULL) {
return;
}
Node* current = head;
Node* prev = NULL;
while (current != NULL && current->data != key) {
prev = current;
current = current->next;
}
if (current == NULL || current->next == head) {
return;
}
Node* temp = current->next;
current->next = temp->next;
delete temp;
}
void deleteByPosition(int position) {
if (position <= 0) {
deleteBegin();
} else {
Node* current = head;
Node* prev = NULL;
for (int i = 0; i < position; i++) {
if (current == head) {
return;
}
prev = current;
current = current->next;
}
prev->next = current->next;
delete current;
}
}
void display() {
if (head == NULL) {
cout << "List is empty" << endl;
return;
}
Node* current = head;
do {
cout << current->data << " ";
current = current->next;
} while (current != head);
cout << endl;
}
};
int main() {
CircularLinkedList list;
int choice, value, key, position;
while (true) {
cout << "1. Insert at beginning\n"
<< "2. Insert at end\n"
<< "3. Insert after a specific element\n"
<< "4. Insert at a specific position\n"
<< "5. Delete from beginning\n"
<< "6. Delete from end\n"
<< "7. Delete the element after a specific element\n"
<< "8. Delete from a specific position\n"
<< "9. Display the list\n"
<< "10. Exit\n"
<< "Enter your choice: ";
cin >> choice;
switch (choice) {
case 1:
cout << "Enter the value to insert: ";
cin >> value;
list.insertBegin(value);
cout << "Element inserted at the beginning.\n";
break;
case 2:
cout << "Enter the value to insert: ";
cin >> value;
list.insertEnd(value);
cout << "Element inserted at the end.\n";
break;
case 3:
cout << "Enter the key element: ";
cin >> key;
cout << "Enter the value to insert: ";
cin >> value;
list.insertAfter(key, value);
cout << "Element inserted after " << key << ".\n";
break;
case 4:
cout << "Enter the position: ";
cin >> position;
cout << "Enter the value to insert: ";
cin >> value;
list.insertByPosition(position, value);
cout << "Element inserted at position " << position << ".\n";
break;
case 5:
list.deleteBegin();
cout << "Element deleted from the beginning.\n";
break;
case 6:
list.deleteEnd();
cout << "Element deleted from the end.\n";
break;
case 7:
cout << "Enter the key element: ";
cin >> key;
list.deleteAfter(key);
cout << "Element deleted after " << key << ".\n";
break;
case 8:
cout << "Enter the position: ";
cin >> position;
list.deleteByPosition(position);
cout << "Element deleted from position " << position << ".\n";
break;
case 9:
cout << "Current list: ";
list.display();
break;
case 10:
cout << "Exiting program.\n";
exit(0);
default:
cout << "Invalid choice. Please try again.\n";
}
}
return 0;
}
