1 ListNode* Merge(ListNode* pHead1, ListNode* pHead2)
 2 {
 3     if (pHead1 == NULL)
 4         return pHead2;
 5     else if (pHead2 == NULL)
 6         return pHead1;
 7     ListNode *pNewHead = NULL, *pNode1 = NULL, *pNode2 = NULL;
 8     if (pHead1->m_nValue <= pHead2->m_nValue)
 9     {
10         pNewHead = pHead1;
11         pNode1 = pHead1->m_pNext;
12         pNode2 = pHead2;
13     } 
14     else
15     {
16         pNewHead = pHead2;
17         pNode1 = pHead1;
18         pNode2 = pHead2->m_pNext;
19     }
20 
21     ListNode* pNewListLastNode = pNewHead;
22 
23     while (pNode1 != NULL && pNode2 != NULL)
24     {
25         if (pNode1->m_nValue <= pNode2->m_nValue)
26         {
27             pNewListLastNode->m_pNext = pNode1;
28             pNewListLastNode = pNode1;
29             pNode1 = pNode1->m_pNext;
30         } 
31         else
32         {
33             pNewListLastNode->m_pNext = pNode2;
34             pNewListLastNode = pNode2;
35             pNode2 = pNode2->m_pNext;
36         }
37     }
38 
39     // 一个链表遍历完了，另一个直接链接到后面即可
40     if (pNode1 == NULL)
41     {
42         pNewListLastNode->m_pNext = pNode2;
43     }
44     else
45     {
46         pNewListLastNode->m_pNext = pNode1;
47     }
48 
49     return pNewHead;
50 }