DSA/linkedlist1.cpp at main · tanishkasaxena/DSA · GitHub

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#include <iostream>
using namespace std;

class node
{
public:
    int data;
    node *next;

    node(int val)
    {
        data = val;
        next = NULL;
    }
};

void makecycle(node *&head, int pos)
{
    node *temp = head;
    node *startnode;

    int count = 1;
    while (temp->next != NULL)
    {

        if (count == pos)
        {
            startnode = temp;
        }
        temp = temp->next;
        count++;
    }
    temp->next = startnode;
}

void insert(node *&head, int val)
{
    node *n = new node(val);

    if (head == NULL)
    {
        head = n;
        return;
    }

    node *temp = head;
    while (temp->next != NULL)
    {
        temp = temp->next;
    }
    temp->next = n;
}

void display(node *head)
{
    node *temp = head;
    while (temp != NULL)
    {
        cout << temp->data << "->";
        temp = temp->next;
    }
    cout << "NULL" << endl;
}

bool detectecycle(node *&head)
{
    node *slow = head;
    node *fast = head;

    while (fast->next != NULL && fast->next->next != NULL)
    {
        slow = slow->next;
        fast = fast->next->next;

        if (fast == slow)
        {
            return true;
        }
    }
}

int main()
{
    node *head = NULL;
    insert(head, 1);
    insert(head, 2);
    insert(head, 3);
    insert(head, 4);
    insert(head, 5);
    insert(head, 6);
    display(head);
    makecycle(head, 3);
    cout << detectecycle(head) << endl;

    return 0;
}