线性链表问题求助

好长的程序

#include<iostream>
 using namespace std;
 typedef int elemtype;
 struct lnode
 {
     elemtype data;
     lnode *next;
 };
 
void createlist_one(lnode *&l,int n)//表头插法
 {
     lnode *p;
     l=new lnode;
     l->next=NULL;
     for(int i=0;i<n;i++)
     {
     
        p=new lnode;
         cout<<"请输入第"<<i+1<<"个数：";
         cin>>(p->data);
         p->next=l->next;
         l->next=p;
delete p;
     
    }
delete l;
 }
 
void createlist_two(lnode *&l,int n)//表尾插法
 {
     l=new lnode;
     l->next=NULL;
     lnode *ptr=l,*p;
     for(int i=0;i<n;i++)
     {
         p=new lnode;
     ptr->next=p;
     cout<<"请输入第"<<i+1<<"个数：";
     cin>>p->data;
     ptr=p;
delete p;
     }
delete l;
 }
 

int insertlist(lnode *&l,int &n)
 {
     lnode *p=l,*s;
     int j;
     cout<<"请输入需要插入的位置:";
     cin>>j;
     for(int i=0;i<j-1&&p;i++)
     {
         p=p->next;
     }
     if(!p||i>j-1)
         return 0;
     s=new lnode;
     cout<<"请输入需要插入的值:";
     cin>>s->data;
     s->next=p->next;
     p->next=s;
     n++;
delete s;
     return 1;
 }
 
int deletelist(lnode *&l, int &n)
 {
     lnode *p=l,*q;
     int j;
     cout<<"请输入需要删除的位置:";
     cin>>j;
     for(int i=0;i<j-1&&p->next;i++)
     {
         p=p->next;
     }
     if(!(p->next)||i>j-1)
         return 0;
     q=p->next;
     p->next=q->next;
     free( q );
     n--;
     return 1;
 }
 
void mergelist(lnode *&la,lnode *&lb,lnode *&lc)
 {
     lnode *pa,*pb,*pc;
     pa=la->next;
     pb=lb->next;
     pc=lc=la;
     while(pa&&pb)
     {
         if(pa->data<=pb->data)
         {
             pc->next=pa;
             pc=pa;
             pa=pa->next;
         }
         else
         {
             pc->next=pb;
             pc=pb;
             pb=pb->next;
         }
     }
     pc->next=pa?pa:pb;
 

   
}
 

void outputlist(lnode *l,int n)//输出
 {
     lnode *p=l;
     for(int j=0;j<=n-1;j++)
     {
         p=p->next;
         cout<<p->data<<" ";
     }
      
     cout<<endl;
 }
 int main()
 {
     lnode *l,*la,*lb,*lc;
     int n=5;
     createlist_two(l,n);
     outputlist(l,n);
     insertlist(l,n);
     outputlist(l,n);
     deletelist(l,n);
     outputlist(l,n);
     createlist_two(la,n);
     createlist_two(lb,n);
     createlist_two(lc,0);
     mergelist(la,lb,lc);
     outputlist(lc,10);
     return 0;
 }