[Leetcode]-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.

题目：合并两个排序后的单链表，要求合并之后也是排序好的

思路：递归合并

/**
* Definition for singly-linked list.
* struct ListNode {
*     int val;
*     struct ListNode *next;
* };
*/
struct ListNode* mergeTwoLists(struct ListNode* l1, struct ListNode* l2) {
if(NULL == l1) return l2;
if(NULL == l2) return l1;

struct ListNode* MergeList = NULL;

if(l1->val < l2->val)
{
MergeList = l1;
MergeList->next = mergeTwoLists(l1->next,l2);
}

else
{
MergeList = l2;
MergeList->next = mergeTwoLists(l1,l2->next);
}

return MergeList;
}