ListNode *temp = head->next; head->next = temp->next; free(temp);
ListNode *p = head; while(p->next != rear) p = p->next; p->next = NULL; free(r); r = p;
new_point->next = head->next; head->next = new_point;
new_point->next = NULL; rear->next = new_point; rear = new_point;