leetcode-21-merge two sorted lists

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.

合并两个已排好序的单向链表

非常简单的链表基本操作，实现即可。

/**
 * 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) return l2;
        if(!l2) return l1;
        ListNode* l3;
        if(l1->val<l2->val)
        {
            l3=l1;
            l3->next=mergeTwoLists(l1->next,l2);
        }else{
            l3=l2;
            l3->next=mergeTwoLists(l1,l2->next);
        }
        return l3;
    }
};