A. p->next=s;s->next=q B. q->next=s;s->next=p C. S->next=p->next;p->next=s D. p->next=s->next;s->next=q
A.O(n) B.O(n log2n) C.O(1) D.O(log2n)
A.n/2 B.(n-1)/2 C.n D.n+1