qkll

#include <iostream>

using namespace std;

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

node * newnode (int x);
void quicksort(node ** begin, node ** end);

int main (void)
{
    int foo,n,i,j,k;
    node * temp;
    node * head = NULL;
    node * tail = NULL;
    cout<<"How many nodes do you want to insert\n";
    cin>>n;
    cout<<"Enter data of linked list\n";
    for ( i = 0; i < n; i++ )
    {
        cin>>foo;
        node * bar;
        if (head == NULL)
        {
            head = newnode(foo);
            tail = head;
        }
        else
        {
            bar = newnode(foo);
            tail->next = bar;
            tail = bar;
        }
    }
    cout<<"The linkedlist that you entered is as follows\n"; // Taking input
    temp = head;
    node * prev = NULL;
    while (temp != NULL)
    {
        cout<<temp->data<<"\t";
        prev = temp;
        temp = temp->next;
    }
    cout<<"\n";
    cout<<"Sorting the linked list now\n"; // Calling sort function
    quicksort(&head,&prev);
    temp = head;
    while (temp != NULL) // Printing output
    {
        cout<<temp->data<<"\t";
        temp = temp->next;
    }
    return 0;
}

node * newnode (int x) // for allocating a new node
{
    node * foo = new node;
    foo->data = x;
    foo->next = NULL;
    return foo;
}

void quicksort(node ** begin, node ** end) // actual sort function
{
    if (*begin == *end)
        return;

    node * pivot = *begin;
    node * temp = *begin;
    temp = temp->next; // for pointing to next element

    while (temp != *end)
    {
        if (temp->data < pivot->data)
        {
            node * temp1 = *begin;  // swapping the two nodes if less than pivot
            *begin = temp;
            temp = temp->next;
            (*begin)->next = temp1;
        }
        else
            temp = temp->next; //else moving to next
    }
    quicksort(begin,&pivot); // calling for remaining elements (first half)
    quicksort(&(pivot->next),end); //for second half
}