leetcode:Merge Two Sorted Lists（有序链表的归并）

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

分析：思路比较简单，遍历两个有序链表，每次指向最小值。

code如下：

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/**  * Definition for singly-linked list.  * struct ListNode {  *     int val;  *     ListNode *next;  *     ListNode(int x) : val(x), next(NULL) {}  * };  */ class Solution { public:     ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {         ListNode *h = new ListNode(0), *p = h;         while(l1 != NULL && l2 != NULL)         {             if(l1 -> val < l2 -> val)             {                 p -> next = l1;                 l1 = l1 -> next;             }             else             {                 p -> next = l2;                 l2 = l2 -> next;             }             p = p -> next;         }         if(l1 != NULL)             p -> next = l1;         if(l2 != NULL)             p -> next = l2;         return h -> next;     } };