Merge linked lists

Lets see how we can merge 2 sorted linked lists into a single sorted linked list.

Idea

Linked list 1    Linked list 2                     Linked list 3          

c1                 c2                 2 < 4            p
4-->6-->8          2-->5-->7        Advance c2         2


c1                     c2             4 < 5                p
4-->6-->8          2-->5-->7        Advance c1         2-->4 


    c1                 c2             5 < 6                    p                        
4-->6-->8          2-->5-->7        Advance c2         2-->4-->5


    c1                     c2         6 < 7                        p                     
4-->6-->8          2-->5-->7        Advance c1         2-->4-->5-->6


        c1                 c2         7 < 8                            p                
4-->6-->8          2-->5-->7        Advance c2         2-->4-->5-->6-->7


                                    List 2 ends        2-->4-->5-->6-->7-->8
                                    Put rem elements 
                                    of list 1

Complete code