A doubly-linked list is a structure similar to a linked list that not only points to the next node, but the previous as well. The next few questions deal with this (unordered) doubly-linked list and its structure; p and q are pointers to some of the elements of the list, as shown:

struct l {

struct l *prev;

struct l *next;

int data;

} *p, *q, *r, *s, *list;

To remove the node with the value 45,

r = p->next; r->next = p->next; r->next->prev = p; free( r );

r = p->next; p->next = r->next; r->next->prev = p; free( p );

p->next->prev = p; p->next = p->next->next; free( p->next );

r = p->next; p->next = r->next; r->next->prev = p; free( r );

p->next = p->next->next; p->next->prev = p; free( p->next );