#define _CRT_SECURE_NO_WARNINGS

#include<stdio.h>

#include<malloc.h>

#define LEN sizeof(struct Node)

struct Node

{

    int data;

    struct Node* Next;

};

typedef struct Node *PtrToNode;

typedef PtrToNode List;//表

typedef PtrToNode Position;//位置

List ReCreatTable(int n);//逆序建立单链表

void PrintTable(Position head);//遍历单链表

void Insert5th(Position head);//在单链表第五个元素前插入一个值为999的元素

void Delete5th(Position head);//删除单链表第五个元素

List ReCreatTable(int n)

{

    int  i;

    Position p, head;

    head = (Position)malloc(LEN);

    head->Next = NULL;

    for (i = ; i <= n; i++)

    {

        p = (Position)malloc(LEN);

        printf("请输入元素:");

        scanf("%d", &p->data);

        p->Next = head->Next;

        head->Next = p;

    }

    return (head);

}

void PrintTable(Position head)

{

    Position s;

    s = head->Next;

    printf("链表:");

    while (s != NULL)

    {

        if (s->Next == NULL)

            printf("%d\n", s->data);

        else

            printf("%d ", s->data);

        s = s->Next;

    }

}

void Insert5th(Position head)

{

    Position P, TmpCell;

    TmpCell = (Position)malloc(LEN);

    P = head;

    int i;

    for (i = ; i < ; i++)

    {

        P = P->Next;

    }

    if (TmpCell == NULL)

        printf("Out of space!!!");

    TmpCell->data = ;

    TmpCell->Next = P->Next;

    P->Next = TmpCell;

}

void Delete5th(Position head)

{

    Position P, TmpCell;//TemCell是删除元素

    P = head;

    int i;

    for (i = ; i < ; i++)

    {

        P = P->Next;

        TmpCell = P->Next;

    }

    P->Next = TmpCell->Next;

    free(TmpCell);

}

int main()

{

    int n;

    Position head;

    printf("请输入链表元素个数:");

    scanf("%d", &n);

    head = ReCreatTable(n);

    PrintTable(head);

    printf("在第五个元素前插入999后");

    Insert5th(head);

    PrintTable(head);

    printf("删除第五个元素后");

    Delete5th(head);

    PrintTable(head);

    return ;

}