要求将hb表归到ha表中

List Union( List ha, List hb )
//ha,hb是两个无头结点的数据域值递增有序的单链表
//本算法实现将hb中不出现在ha中的数据合并到ha中，同时合并中不破坏hb链表
{
    List head = (List)malloc(sizeof(LNode));
    head->next = ha;
    Lnode pa,pb,pTmp;
    pa = ha;
    pb = hb;
    pTmp = head;//pTmp指向当前待合并结点的前驱
    
    while ( pa&&pb ) {
        if ( pa->data < pb->data ) {
            pTmp->next = pa;
            pTmp = pa;
            pa = pa->next;            
        }
        else if ( pa->data > pb->data ) {
            Lnode Lr = (Lnode)malloc(sizeof(Lnode));
            Lr->data = pb->data;
            pTmp->next = Lr;
            pb = pb->next;
        }
        else {//pa->data == pb->data
            pTmp->next = pa;
            pTmp = pa;
            pa = pa->next;
            pb = pb->next;
        }
    }
    
    if ( pa ) {
        pTmp->next = pa;
    }
    else {
        while ( pb ) {
            Lnode  Lr = (Lnode)malloc(sizeof(Lnode));
            Lr->data = pb->data;
            pTmp->next = Lr;
            pTmp = Lr;
            pb = pb->next;
        }
        pTmp->next = NULL;
    }
    
    free(head);
    return ha;
}