Concatenation of two Linked Lists

Let us assume that the two linked lists are referenced by head1 and head2 respectively.

1. If the first linked list is empty then return head2.

2. If the second linked list is empty then return head1.

3. Store the address of the starting node of the first linked
list in a pointer variable, say p.

4. Move the p to
the last node of the linked list through simple linked list traversal
technique.

5. Store the address of the first node of the second linked
list in the next field of the node pointed by p. Return head1.

Also Read: C++ Program for Linked List Representation of Linear Queue

Also Read: Menu Driven C Program to Perform Insert, Display and Delete Operations on a Singly Linked List (SLL)

node * concatenate (node *head1, node *head2)

{

                node
*p;

                if (head1==NULL)                            //if the first linked
list is empty

                                return
(head2);

                if (head2==NULL)                            //if second linked
list is empty

                                return
(head1);

               

                p=head1;                             //place p on the first
node of the first linked list

               

                while (p->next!=NULL)                 //move p to the last node

                                p=p->next;

                p->next=head2;                           //address
of the first node of the second linked list stored in the last node of the
first linked list

                

                return
(head1);

}