#include<iostream>

using namespace std;

class ListNode {

public :

    int data;

    ListNode *next;

};

class List {

public:

    List();

    ~List();

    void CreateList();

    void Insert(int data,int index,bool flag = true);

    void Delete(int index);

    void printList();

    void getData(int index);

    int getLength();

private:

    ListNode *head;

};

List::List() {

    head = new ListNode();

    head->next = NULL;

    cout<<"创建对象成功"<<endl;

}

List::~List() {

    ListNode *p = head, *s;

    while (p->next != NULL) {

        s = p->next;

        p = s->next;

        delete s;

    }

    delete p;

    delete head;

}

int List::getLength() {

    int len = 0;

    ListNode *p = head;

    while(p->next != NULL) {

        len++;

        p = p->next;

    }

    return len;

}

void List::CreateList() {

    int num,data;

    cout<<"请输入数据个数";

    cin>>num;

    cout<<endl;

    cout<<"请输入数据";

    cout<<endl;

    for(int i = 0;i<num;i++) {

        cin>>data;

        Insert(data,getLength()+2,false);

    }

    cout<<"List 创建完成"<<endl;

}

void List::Insert(int data,int index,bool flag) {

    ListNode *p = head, *s;

    if(index<=0) {

        cout<<"数据长度必须大于0";

        return ;

    }

    if(getLength()+1<index) {

        while (p->next != NULL)

        {

            p = p->next;

        }

        s = (ListNode*)new ListNode[1];

        s->data = data;

        s->next = NULL;

        p->next = s;

        if(flag!=false) {

            cout<<"链表长度为"<<getLength()-1<<",无法插入到第"<<index<<"个位置";

            cout<<"现将数据"<<data<<"插入到表尾部"<<endl;

        }

    }

    else {

        for(int i =0;i<index-1;i++) {

            p = p->next;

        }

        s = (ListNode*)new ListNode[1];

        s->data = data;

        s->next = p->next;

        p->next = s;

        cout<<"数据"<<data<<"插入第"<<index<<"个位置成功！"<<endl;

    }

}

void List::Delete(int index) {

    ListNode *p = head, *s;

    int i =0;

    if(index<=0||index>getLength()) {

        cout<<"元素不在表中"<<endl;

        return ;

    }

    while(i<index-1)

    {

        i++;

        p = p->next;

    }

        s= p->next;

        p->next = s->next;

        cout<<"第"<<index<<"个元素删除成功!"<<endl;

        delete s;

}

void List::printList() {

    ListNode *p = head;

    cout<<"printList:"<<endl;

    if(p->next==NULL) {

        cout<<"空链表"<<endl;

        return ;

    }

    p= p->next;

    while(p!= NULL) {

        cout<<p->data<<" ";

        p=p->next;

    }

    cout<<endl;

}

void List::getData(int index) {

    ListNode *p = head;

    if(index<=0||index>getLength()) {

        cout<<"元素不在表中"<<endl;

        return ;

    }

    for(int i = 0;i<index;i++) {

        p = p->next;

    }

    cout<<"第"<<index<<"个元素为"<<p->data<<endl;

}

int main() {

    List list;

    list.CreateList();

    list.printList();

    list.Insert(10,2);

    list.Insert(20,10);

    list.printList();

    list.Delete(5);

    list.printList();

    list.getData(4);

    cout<<"目前链表长度为"<<list.getLength()<<endl;

    return 0;

}