circular linked list.cpp

#include<bits/stdc++.h>
using namespace std;

struct Node
{
    int data;
    struct Node* next;
};

struct Node* addToEmpty(struct Node* last, int data)
{
    if (last != NULL)
        return last;
    struct Node* temp =
        (struct Node*)malloc(sizeof(struct Node));
    temp->data = data;
    last = temp;

    last->next = last;

    return last;
}

struct Node* addBegin(struct Node* last, int data)
{
    if (last == NULL)
        return addToEmpty(last, data);

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

    temp->data = data;
    temp->next = last->next;
    last->next = temp;

    return last;
}

struct Node* addEnd(struct Node* last, int data)
{
    if (last == NULL)
        return addToEmpty(last, data);

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

    temp->data = data;
    temp->next = last->next;
    last->next = temp;
    last = temp;

    return last;
}

struct Node* addAfter(struct Node* last, int data, int item)
{
    if (last == NULL)
        return NULL;

    struct Node* temp, * p;
    p = last->next;
    do
    {
        if (p->data == item)
        {
            temp = (struct Node*)malloc(sizeof(struct Node));
            temp->data = data;
            temp->next = p->next;
            p->next = temp;

            if (p == last)
                last = temp;
            return last;
        }
        p = p->next;
    } while (p != last->next);

    cout << item << " not present in the list." << endl;
    return last;

}

void traverse(struct Node* last)
{
    struct Node* p;

    if (last == NULL)
    {
        cout << "List is empty." << endl;
        return;
    }

    p = last->next;

    do
    {
        cout << p->data << " ";
        p = p->next;

    } while (p != last->next);

}

int main()
{
    struct Node* last = NULL;

    last = addToEmpty(last, 6);
    last = addBegin(last, 4);
    last = addBegin(last, 2);
    last = addEnd(last, 8);
    last = addEnd(last, 12);
    last = addAfter(last, 10, 8);

    traverse(last);

    return 0;
}