单链表合并

//有序单链表合并
Node *MergeList(Node *head1, Node *head2)
{
    Node *p1 = NULL;
    Node *p2 = NULL;
    Node *head = NULL;

    if (head1->data < head2->data)
    {
        head = head1;
        p1 = head1->next;
        p2 = head2->next;
    }
    else
    {
        head = head2;
        p2 = head2->next;
        p1 = head1->next;
    }

    Node *pre = head;

    while (p1 != NULL && p2 != NULL)
    {
        if (p1->data < p2->data)
        {
            pre->next = p1;
            pre = p1;
            p1 = p1->next;
        }
        else
        {
            pre->next = p2;
            pre = p2;
            p2 = p2->next;
        }
    }

    if (p1 ！= NULL)
    {
        pre->next = p1;
    }

    if (p2 != NULL)
    {
        pre->next = p2;
    }

    return head;
}