Singly Linked List - Add Operation

Inserting an element in Middle of the Linked List :

Consider :

            3 ---> 4 ---> 5 ---> 7

                     prev    next

 Suppose we want to insert an element with value 8 after 4 .

     1. Initialize a new node cur with given value 8.

                    cur.value =  8;

     2.  Link the cur next node to prev next node next.

                   cur.next = prev.next;

     3.  Link the prev next node to current node.

                   prev.next = current;

So here we no need to move all the elements like arrays.  So we can insert the element in List in O(1) time complexity. Which is very efficient.

Inserting an element at the Beginning :

    In list we use the head node to represent the entire list. 

    So we should update the head when representing the entire list.

   1. First create a new node current with the value.

   2. Second point current node next to head node.

  3.  Update the head node by pointing to current node.