题目
输入两个递增排序的链表，　合并这两个链表并使新链表中的结点仍然是依照递增排序的．

ListNode* Merge(ListNode* pHead1, ListNode* pHead2)
{
    if (pHead1 == NULL) 
        return pHead2;
    else if (pHead2 == NULL)
        return pHead1;

    ListNode* MergeHead = NULL;
    if (pHead1->m_nValue < pHead2->m_nValue)
    {
        MergeHead = pHead1;
        MergeHead->m_pNext = Merge(pHead1->m_pNext, pHead2);
    }
    else
    {
        MergeHead = pHead2;
        MergeHead->m_pNext = Merge(pHead1, pHead2->m_pNext);
    }

    return MergeHead;
}