建链表及插入操作

#include<iostream>
using namespace std;
/*******establish struct***************/
struct student
{
 int score;
 struct student *next;
};
student *header;
/***********establish linklist********/
student *creat()
{
 student *ps,*pend;
 header=NULL;
 ps=new student;
 cin>>ps->score;
 pend=ps;
 while(ps->score!=0)
 {
  if(header==NULL)
      header=ps;
  else
      pend->next=ps;
  pend=ps;
  ps=new student;
  cin>>ps->score;
 }
    pend->next=NULL;
    delete ps;
    return header;
}
/*************showlist()*************/
void showlist(student *p)
{
 while(p)
 {
  cout<<p->score<<endl;
  p=p->next;
 }
}
/***************insert noder*********/
void insert(student* pt)
{
 if(header==NULL)      
 {
  header=pt;
  pt->next=NULL;
  return;
 }
 if(header->score>pt->score)
 {
     pt->next=header; 
     header=pt;
     return;
 }
 for(student* p=header;p->next;p=p->next)
 {
  if(p->next->score>pt->score)
  {
   pt->next=p->next;
   p->next=pt;
   return;
  }
 }
 p->next=pt;
 pt->next=NULL;       
 return;
}     
/**********main()*******************/
int main()
{
    header=creat();
    struct student std;
    cin>>std.score;std.next=NULL;
    insert(&std);
    showlist(header);

    return 0;
}