面试题17：合并两个排序的链表

题目描述

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按照递增排序的。例如输入图3.7中的链表1和链表2，则合并之后的升序链表如链表3所示。链表结点定义如下：

题目分析

剑指Offer（纪念版）P114

代码实现

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

    ListNode* pMergedHead = NULL;

    if(pHead1->m_nValue < pHead2->m_nValue)
    {
        pMergedHead = pHead1;
        pMergedHead->m_pNext = Merge(pHead1->m_pNext, pHead2);
    }
    else
    {
        pMergedHead = pHead2;
        pMergedHead->m_pNext = Merge(pHead1, pHead2->m_pNext);
    }

    return pMergedHead;
}