合并两个排序的链表

 1 /*
 2 struct ListNode {
 3     int val;
 4     struct ListNode *next;
 5     ListNode(int x) :
 6             val(x), next(NULL) {
 7     }
 8 };*/
 9 class Solution {
10 public:
11     ListNode* Merge(ListNode* pHead1, ListNode* pHead2)
12     {
13         if(pHead1==NULL)
14             return pHead2;
15         else if(pHead2==NULL)
16             return pHead1;
17 
18         ListNode * pNode1=pHead1;//尽量不在原来的指针上进行改动
19         ListNode * pNode2=pHead2;       
20         ListNode *pMergeHead=NULL;
21         if(pNode1->val<pNode2->val)
22         {
23             pMergeHead=pNode1;
24             pMergeHead->next=Merge(pNode1->next,pNode2);
25         }else
26         {
27             pMergeHead=pNode2;
28             pMergeHead->next=Merge(pNode1,pNode2->next);
29         }
30 
31         return pMergeHead;
32 
33     }
34 };