题解 | #合并两个排序的链表#

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) :
            val(x), next(NULL) {
    }
};*/
//水过，如果看不懂@我，我再加注释
class Solution {
public:
    ListNode* Merge(ListNode* pHead1, ListNode* pHead2) {
        ListNode *p1,*p2,*pre;
        p1=pHead1,p2=pHead2,pre=pHead1;
        while(p1!=NULL&&p2!=NULL)
        {
            if(p2->val<=p1->val)
            {
                if(p1==pHead1)
                {
                    ListNode *temp=p2->next;
                    p2->next=p1;
                    pHead1=p2;
                    p2=temp;
                    pre=pHead1;
                }
                else
                {
                    ListNode *temp=p2->next;
                    p2->next=p1;
                    pre->next=p2;
                    p2=temp;
                    pre=pre->next;
                }
            }
            else
            {
                if(p1==pHead1)
                {
                    p1=p1->next;
                }
                else
                {
                    p1=p1->next;
                    pre=pre->next;
                }
            }
        }
        if(p2==NULL)
        return pHead1; 
        else
        {
            pre->next=p2;
            return pHead1;
        }
    }
};