Reversing a single linked list !

Hello everybody !

This one questions is one of most commonly asked interview questions if you appear for a system programming job . Let me try to write the program for it in most simple way .

Let us consider we have 4 nodes A->B->C->D , to arrange these nodes in reverse order , let us first

• Take the first node 'A' and detach from the link , 
• Make the next of A as NULL 
• Make B as root 

Now , let us go through the first list and detach it from main link and connect it to second link . 

We need to repeat these steps till we reach NULL for the main list , once we are done with the traversing  - its the time for declaring new head as our head :-)

You can get the C code for the same below .

void reverse_list()

{

  struct list *temp ;

  new = head ;

/*Detaching the first node from the main list */

  temp =head->next;

  head = head->next;

  new->next =NULL;

/*Traverse through the main list and attach each node to new list 

   that we are trying to create !*/

  while (temp!= NULL)

  {

    temp = head->next;

    head->next=new;

    new = head ;

    head =temp;

  }

  head = new;

}

Adding & displaying a single linked list you can take as exercise  !!

Enjoy reversing !!