题解 | #合并两个排序的链表#

尾插法

//尾插法
struct ListNode* Merge(struct ListNode* pHead1, struct ListNode* pHead2 ) 
{
    if(pHead1==NULL)
    {
        return pHead2;
    }
    if(pHead2==NULL)
    {
        return pHead1;
    }
    
    struct ListNode* Head=NULL;
    struct ListNode* Tail=NULL;
    while(pHead1!=NULL&&pHead2!=NULL)
    {
        if((pHead1->val)<(pHead2->val))
       {
            if(Head==NULL)
            {
            Head=pHead1;
            //找小的为首结点
            Tail=Head;
            }
            else
            {
                Tail->next=pHead1;
                Tail=Tail->next;
            }
            pHead1=pHead1->next;
       }
        else
        {
            if(Head==NULL)
            {
            Head=pHead2;
            //找小的为首结点
            Tail=Head;
            }
            else
            {
                Tail->next=pHead2;
                Tail=Tail->next;
            }
            pHead2=pHead2->next;
        }
    }
        if(pHead2==NULL)
        {
            Tail->next=pHead1;
            Tail=Tail->next;
        }
        if(pHead1==NULL)
        {
            Tail->next=pHead2;
            Tail=Tail->next;
        }
    return Head;
}