Leetcode:Merge Two Sorted Lists 合并两个有序单链表

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.

代码如下：

* 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) {        if(l1 == NULL)return l2;        if(l2 == NULL)return l1;                ListNode dummy(0);                ListNode *tail = &dummy;        ListNode *cur = NULL;                while(l1 != NULL && l2 != NULL)        {            if(l1->val >= l2->val)            {                cur = l2;                l2 = l2->next;            }            else            {                cur = l1;                l1 = l1->next;            }            tail->next = cur;            tail = cur;        }        if(l1 != NULL)            tail->next = l1;        if(l2 != NULL)            tail->next = l2;                return dummy.next;    }};