How to insert a new node to a single-linked list, where we do not have a pointer pointed to its head?

Question

Given a pointer that points to an intermediate node (non-head, non-tail) on a single-link list . How to insert a new node just before the node pointed to by the given pointer ?

Example, Given single-linked list:

  A -> B -> C -> D -> E 

Given a pointer pointed to C (ptr = &C), and a new node F, how to get

 A -> B -> F -> C -> D -> E 

Attention: we do not have pointers pointed to A.

Thanks

Answer 1

You should be able to implement this by inserting a new C node to the right, and writing F in the data field of the initial C node.

Answer 2

Obviously, It can't be done. If you need that capability, use a doubly-linked list. Otherwise, always pass along a pointer to the head of the list.