LeetCode 21. 合并两个有序链表

/**
 * 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) {
        auto l=new ListNode(-1);
        auto cur=l;
        auto p=l1,q=l2;
        while(p&&q){
            if(p->val>q->val){
                cur->next=q;
                q=q->next;
            }
                
            else{
                cur->next=p;
                p=p->next;
            }
                
            cur=cur->next;
        }
        cur->next=p?p:q;
        return l->next;
    }
};