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.

s思路：

1. 常规题。就是考察对list的操作，需要边比较边根据比较的结果来觉得移动两个list中的那一个的指针。

//方法１：用recursive的方法来比较
class Solution {
public:
ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {

if(!l1) return l2;
if(!l2) return l1;
if(l1->val>l2->val){
l2->next=mergeTwoLists(l1,l2->next);
return l2;
}else{
l1->next=mergeTwoLists(l1->next,l2);
return l1;
}
}
};