合并两个排序的链表

class Solution {
public:
    ListNode* Merge(ListNode* pHead1, ListNode* pHead2) {
        ListNode* head=new ListNode(0);//创建合成链表
        ListNode* cur=head;
        if(pHead1==NULL)
            return pHead2;
        if(pHead2==NULL)
            return pHead1;
        while(pHead1&&pHead2)
        {
            if(pHead1->val<=pHead2->val)
            {
                cur->next=pHead1;
                pHead1=pHead1->next;
                cur=cur->next;
            }
            else
            {
                 cur->next=pHead2;
                pHead2=pHead2->next;
                cur=cur->next;
            }
        }
         //讨论到底情况
        if(pHead1)
            cur->next=pHead1;  
        else
            cur->next=pHead2;
        return head->next;
        
    }
};