Save distinct words into linked list

Question

Basically I have 2 linked list here: list and distinct. There are a few set of words which have been saved earlier into the \'list\' struct. Was gonna write a program that i

Answer 1

These three lines is one likely culprit:

if(ori == NULL && copy == NULL) { //first time.
    ori = ori->next;
    copy = copy->next;

Here you check if ori and copy are NULL, then you immediately dereference those NULL pointers!