struct student
{
    char num[5];
    char name[20];
    float score;
    struct student*next;
};
struct student* paixu(struct student*p,int n)//n为接点数
{
    struct student *p1,*p2,*temp,*head;
    int i;
    head=p;
    p1=p;
    p2=p1->next;
    if(n>1)
    for(i=0;i<n-1;i++)
     {do
        {if(strcmp(p1->num,p2->num)>0)
          {p1->next=p2->next;
           p2->next=p1;
           if(p1!=p)
              p->next=p2;
           if(p1==p) //判断被换的接点是不是头接点//
              head=p2;
           temp=p1;
           p1=p2;
           p2=temp;   //p1和p2 的换值是为了让p1始终在p2 前面//
          }
         if(p!=p1&&p!=p2)
           p=p->next;
         else
           p=head;
         p1=p1->next;
         p2=p2->next;
        }while(p1->next!=NUL);
     p=head;
     p1=head;
     p2=p1->next;}//比完一论后在回归头一个接点//
    return(head);   
}