circular_single_linked_list.cpp

#include <iostream>
#include <stdlib.h>
using namespace std;

struct node
{
    int info;
    struct node *next;
} * last;
class circular_llist
{
public:
    void create_node(int value);
    void add_begin(int value);
    void add_after(int value, int position);
    void delete_element(int value);
    void search_element(int value);
    void display_list();
    void update();
    void sort();
    circular_llist()
    {
        last = NULL;
    }
};

int main()
{
    int choice, element, position;
    circular_llist cl;
    while (1)
    {
    	cout << "Press 1 to Create node... Press 2 to Add at begining... Press 3 to Add after\n";
		cout << "Press 4 to Delete... Press 5 to Search... Press 6 to Display\n";
		cout << "Press 7 to Update... Press 8 to Sort... Press 9 to Exit\n";   
        cout << "Operation : ";
        cin >> choice;
        switch (choice)
        {
        case 1:
            cout << "Enter element: ";
            cin >> element;
            cl.create_node(element);
            cout << endl;
            break;
        case 2:
            cout << "Enter element: ";
            cin >> element;
            cl.add_begin(element);
            cout << endl;
            break;
        case 3:
            cout << "Enter element: ";
            cin >> element;
            cout << "Insert element after position: ";
            cin >> position;
            cl.add_after(element, position);
            cout << endl;
            break;
        case 4:
            if (last == NULL)
            {
                cout << "List is empty, nothing to delete" << endl;
                break;
            }
            cout << "Enter the element for deletion: ";
            cin >> element;
            cl.delete_element(element);
            cout << endl;
            break;
        case 5:
            if (last == NULL)
            {
                cout << "List is Empty! Can't search" << endl;
                break;
            }
            cout << "Enter the element to be searched: ";
            cin >> element;
            cl.search_element(element);
            cout << endl;
            break;
        case 6:
            cl.display_list();
            break;
        case 7:
            cl.update();
            break;
        case 8:
            cl.sort();
            break;
        case 9:
            exit(1);
            break;
        default:
            cout << "Wrong choice" << endl;
        }
    }
    return 0;
}

void circular_llist::create_node(int value)
{
    struct node *temp;
    temp = new (struct node);
    temp->info = value;
    if (last == NULL)
    {
        last = temp;
        temp->next = last;
    }
    else
    {
        temp->next = last->next;
        last->next = temp;
        last = temp;
    }
}

void circular_llist::add_begin(int value)
{
    if (last == NULL)
    {
        cout << "First Create the list." << endl;
        return;
    }
    struct node *temp;
    temp = new (struct node);
    temp->info = value;
    temp->next = last->next;
    last->next = temp;
}

void circular_llist::add_after(int value, int pos)
{
    if (last == NULL)
    {
        cout << "First Create the list." << endl;
        return;
    }
    struct node *temp, *s;
    s = last->next;
    for (int i = 0; i < pos - 1; i++)
    {
        s = s->next;
        if (s == last->next)
        {
            cout << "There are less than ";
            cout << pos << " in the list" << endl;
            return;
        }
    }
    temp = new (struct node);
    temp->next = s->next;
    temp->info = value;
    s->next = temp;
    
    if (s == last)
    {
        last = temp;
    }
}

void circular_llist::delete_element(int value)
{
    struct node *temp, *s;
    s = last->next;
   
    if (last->next == last && last->info == value)
    {
        temp = last;
        last = NULL;
        free(temp);
        return;
    }
    if (s->info == value)
    {
        temp = s;
        last->next = s->next;
        free(temp);
        return;
    }
    while (s->next != last)
    {
        
        if (s->next->info == value)
        {
            temp = s->next;
            s->next = temp->next;
            free(temp);
            cout << "Element " << value;
            cout << " deleted from the list" << endl;
            return;
        }
        s = s->next;
    }
    
    if (s->next->info == value)
    {
        temp = s->next;
        s->next = last->next;
        free(temp);
        last = s;
        return;
    }
    cout << "Element " << value << " not found in the list" << endl;
}

void circular_llist::search_element(int value)
{
    struct node *s;
    int counter = 0;
    s = last->next;
    while (s != last)
    {
        counter++;
        if (s->info == value)
        {
            cout << "Element " << value;
            cout << " found at position " << counter << endl;
            return;
        }
        s = s->next;
    }
    if (s->info == value)
    {
        counter++;
        cout << "Element " << value;
        cout << " found at position " << counter << endl;
        return;
    }
    cout << "Element " << value << " not found in the list" << endl;
}

void circular_llist::display_list()
{
    struct node *s;
    if (last == NULL)
    {
        cout << "List is empty, nothing to display" << endl;
        return;
    }
    s = last->next;
    cout << "Circular Link List: " << endl;
    while (s != last)
    {
        cout << s->info << "->";
        s = s->next;
    }
    cout << s->info << endl;
}

void circular_llist::update()
{
    int value, pos, i;
    if (last == NULL)
    {
        cout << "List is empty, nothing to update" << endl;
        return;
    }
    cout << "Enter the node position to be updated: ";
    cin >> pos;
    cout << "Enter the new value: ";
    cin >> value;
    struct node *s;
    s = last->next;
    for (i = 0; i < pos - 1; i++)
    {
        if (s == last)
        {
            cout << "There are less than " << pos << " elements.";
            cout << endl;
            return;
        }
        s = s->next;
    }
    s->info = value;
    cout << "Node Updated" << endl;
}
void circular_llist::sort()
{
    struct node *s, *ptr;
    int temp;
    if (last == NULL)
    {
        cout << "List is empty, nothing to sort" << endl;
        return;
    }
    s = last->next;
    while (s != last)
    {
        ptr = s->next;
        while (ptr != last->next)
        {
            if (ptr != last->next)
            {
                if (s->info > ptr->info)
                {
                    temp = s->info;
                    s->info = ptr->info;
                    ptr->info = temp;
                }
            }
            else
            {
                break;
            }
            ptr = ptr->next;
        }
        s = s->next;
    }
}