data structures - Deleting any node from a single linked list when only pointer to that node is given

Question

This is a question posed to me in an interview.

"A single linked list is there in the memory. You have to delete a node. You need to write a function to delete that node, which takes only the address of the node to be deleted as input and nothing else(including head)"

I gave the answer similar to the one answered in the below post -- Copying the contents of the next node into the node to be deleted and deleting the next one.

Deleting a middle node from a single linked list when pointer to the previous node is not available

But the interviewer asked me again, what if I pass the address of the last node. I told him, since the next will be a NULL, copy that NULL into the data field along with the address to the next node which is also NULL. Then he told me there will be a problem of dangling pointers... which I didn't understand a bit. Can some one please throw light into this problem ? Is there a generic solution to this ?

Update (Two days later) : A little bit additional. Considering there is no special node at the end of the list. And the last node points to NULL and if that node is given as input, how to make the before last node point to NULL. Or is it impossible ?

Simply put : If a node is given as input to a function, how to make the pointer that references it, point to NULL

Answer 1

Steps:

1. Copy data from Node(i+1) to Node(i)
2. Copy the NEXT of second Node(i+1) into a temporary variable.
3. Now Delete the second Node(i+1) // it doesn't require pointer to the previous node.

Function:

void delete_node(node* node)
{
    node->Data = node->Next->Data;
    node* temp = node->Next->Next;
    delete(node->Next);
    node->Next = temp;
}