데이터 구조 실습 2 Debug

#include<stdafx.h>
#include<stdlib.h>
typedef struct student
 {  int  num ; 
    int  score ;
    struct student *next ;
 }ST;
#define   LEN   sizeof(ST)
int  n;
ST *creat(void)
{
	ST *p1,*p2,*head=NULL;
	int n=0;
	p1=(ST *) malloc (LEN); //       
	if(p1==NULL)
	{
		printf("
 No enough memory!
");exit(0);
	}
	scanf("%d %d",&p1->num,&p1->score);
	while ( p1->num!=0 )
	{   
		n=n+1;//     1
        if(n==1)head=p1;// n  1， p1           
        else p2->next=p1;
        p2=p1;//   p2  p1      
        p1=(ST *) malloc (LEN);//p1        
        if(p1==NULL)
		{
			printf("
 No enough memory!
");exit(0);
		}
        scanf("%d %d",&p1->num, &p1->score);
    }
    p2->next =NULL;         //            
    free(p1);//  p1        
    return(head);
} 
void  list(ST *head)
{  
	ST *p;
    p=head;
    while (p!=NULL)
    {
		printf("%d,%d
",p->num,p->score);
        p=p->next ;   
    }
}

ST *del(ST *head, int  num)
{
	ST *p,*q=NULL;
    p=head;
    while((num!=p->num)&&(p->next!=NULL))
    {
		q=p;
		p=p->next;
	}
    if(num==p->num)
    {
		if(p==head)head=p->next;//           
        else q->next=p->next;//              
        free(p);        //          
        n=n-1;     //        1
		printf("deleted ! 
");    
     }
     else printf("can not delete!
");      
     return(head);//        

}

ST *insert(ST *head)
{
	ST *p0,*p1,*p2;
    p1=head;
	p0=(ST*)malloc(LEN);
    scanf("%d%d",&p0->num,&p0->score);
    if(head==NULL)//      ，            
	{
		head=p0;
		p0->next=NULL;
	}
    else
	{
		while((p0->num>p1->num)&&(p1->next!=NULL))
        {
			p2=p1;
			p1=p1->next;
		}//          
        if(p0->num<=p1->num)     
        {
			if(head==p1)head=p0;//         
			else p2->next=p0;//         
            p0->next=p1;
		}
        else  
        {
			p1->next=p0;p0->next=NULL;
		}//         
     }  
     n++;//        1
     return( head ) ;
  } 
void main()
 {
	ST *h=NULL;
    h=creat();
    list(h);
    h=del(h,2);
    list(h);
    h=insert(h);
    list(h);
}