#include "stdafx.h"
#include "malloc.h"
#include "stdlib.h"
#include "stdio.h"
#define NULL 0
#define LEN sizeof(struct student)

struct student
{
    long num;
    float score;
    struct student *next;
};

int n;//n为全局变量，指结点数

struct student *creat(void)
{
    struct student *head;
    struct student *p1,*p2;
    n=0;
    p1=p2=(struct student *)malloc(LEN);//开辟结点，使p1、p2指向它
    scanf("%ld%f",&p1->num,&p1->score);
    head=NULL;//此时链表中无结点
    while(p1->num!=0)//约定学生学号不为0，如果学号为0，代表链表创建结束
    {
        n=n+1;
        if(n==1)//判断是否是第一个结点
            head=p1;//head指向首结点
        else
            p2->next=p1;//将新结点的地址赋给p2结点的next成员
        p2=p1;//p2指向新结点
        p1=(struct student *)malloc(LEN);
        scanf("%ld%f",&p1->num,&p1->score);
    }
    p2->next=NULL;//链表创建过程结束
    return(head);
}

void print(struct student *head)
{
    struct student *p;
    printf("\nNow,these %d records are:\n",n);
    p=head;//p指向第一个结点
    if(head!=NULL)
        do
        {
            printf("%ld%5.1f\n",p->num,p->score);
            p=p->next;
        }while(p!=NULL);
}

struct student *del(struct student *head,long num)
{
    struct student *p1,*p2;
    if(head==NULL)//判断链表是否为空
    {
        printf("\nlist null!\n");
    }
    else
    {
        p1=head;
        while(num!=p1->num&&p1->next!=NULL)
        {
            p1=p2;
            p1=p1->next;//p1后移一个结点
        }
        if(num==p1->num)
        {
            if(p1==head)
                head=p1->next;
            else
                p2->next=p1->next;//让p1的前一个结点指向其后一个结点
            printf("delete:%ld\n",num);
            n=n-1;
        }
        else
            printf("%ld not been found!",num);//找不到该结点
    }
    return(head);
}

struct student *insert(struct student *head,struct student *stud)
{
    struct student *p0,*p1,*p2;
    p1=head;//p1指向第一个结点
    p0=stud;//p0指向要插入的节点
    if(head==NULL)//判断链表是否为空
    {
        head=p0;
        p0->next=NULL;//p0指向的结点作为头结点
    }
    else
    {
        while((p0->num>p1->num)&&(p1->next!=NULL))
        {
            p2=p1;
            p1=p1->next;//p1后移一个结点
        }
        if(p0->num<=p1->num)
        {
            if(head==p1)//p0是头结点
                head=p0;
            else
                p2->next=p0;
            p0->next=p1;
        }
        else//p0是尾结点
        {
            p1->next=p0;
            p0->next=NULL;
        }
    }
    n=n+1;//结点数加1
    return(head);
}

void main()
{
    struct student *head,*stu;
    long del_num;
    printf("input records:\n");
    head=creat();
    print(head);
    printf("\ninput the deleted number:");
    scanf("%ld",&del_num);
    while(del_num!=0)
    {
        head=del(head,del_num);
        print(head);
        printf("\ninput the deleted number:");
        scanf("%ld",&del_num);
    }
    printf("\ninput the inserted record:");
    stu=(struct student *)malloc(LEN);
    scanf("%ld%f",&stu->num,&stu->score);
    while(stu->num!=0)
    {
        head=insert(head,stu);
        print(head);
        printf("\ninput the inserted record:");
        stu=(struct student *)malloc(LEN);
        scanf("%ld%f",&stu->num,&stu->score);
    }
    free(head);
    system("Pause");
}