/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* merge(ListNode* l1, ListNode* l2) {
ListNode *l=new ListNode(0);
ListNode *p=l;
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 l->next;
}
};