leetcode Merge Two Sorted Lists

代码

class Solution {
public:
    ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
        
        ListNode*head = new ListNode(0);
        ListNode*p1,*p2,*p;
        p = head;
        p1 = l1;
        p2 = l2;
        while(p1!=NULL&&p2!=NULL)
        {
            if(p1->val<=p2->val)
            {
                p->next = p1;
                p1 = p1->next;
            }
            else
            {
                p->next = p2;
                p2 = p2->next;
            }
            
            p = p->next;
            
        }
        
        if(p1!=NULL)
        {
            p->next = p1;
        }
        
        if(p2!=NULL)
        {
            p->next = p2;
        }
        
        return head->next;
        
    }
};