数据结构算法——1007. 环形双向链表的删除操作(待精简

题目

思路

搞清楚环形链表在 开头、 中部、结尾 ，以及链表是否为空？单个元素？多个元素？插入和删除的情况
代码有待精简

代码（未精简

#include<iostream>
using namespace std;
typedef long long ll;


struct node
{
    ll data;
    node* next;
    node* prev;
    node()
    {
        data = 0;
        next = NULL;
        prev = NULL;
        //cout << data << next << prev << "111";
    }

    int append(ll n)
    {
        if(next == NULL)//只有头指针可以操作
        {
            node* temp = new node;
            next = temp;
            temp->data = n;
            temp->next = temp;
            temp->prev = temp;
            return 1;//表示插入成功
        }

        node* record = next;
        node* search = next;
        while(search->next != record)
            search = search->next;//找到尾部
        
        node* temp = new node;
        temp->data = n;
        temp->prev = search;
        temp->next = record;
        record->prev = temp;
        search->next = temp;
        return 1;
        
    };

    int del(ll n)
    {
        int flag = 0;
        if(next == NULL)//空
            return flag;

        node* record = next;
        node* search = next;

        if(search->next == record)//只有一个
        {
            if(search->data == n)
            {
                next = NULL;
                delete search;
                flag = 1;
            }
            return flag;
        }
        else if(search->next != record)//不止一个
        {
            while(record->data == n && search->next != record)
            {
                node*temp = record;
                record->prev->next = record->next;
                record->next->prev = record->prev;

                next = record->next;
                search = record->next;
                record = record->next;
                delete temp;
                flag = 1;
            }
            while(search->next != record)
            {
                if(search->data == n)
                {
                    node* temp = search;
                    search->next->prev = search->prev;
                    search->prev->next = search->next;
                    search = search->next;
                    delete temp;
                    flag = 1;
                }
                else
                {
                    search = search->next;
                }
            }
            //还剩最后一个数据没遍历，可能只有一个
            if(search->next == record && record->next == search)
            {
                if(search->data == n)
                {
                    next = NULL;
                    delete search;
                    flag = 1;
                }
            }
            else
            {
                if(search->data == n)
                {
                    node*temp = search;
                    search->next->prev = search->prev;
                    search->prev->next = search->next;
                    search = search->next;
                    delete temp;
                    flag = 1;
                }
            }
        }
        return flag;
    };


    void print()
    {
        node* record = next;
        if(record == NULL)
        {
            //cout << "nothing" << endl;
            return;
        }


        node* search = next;
        while(search->next != record)
        {
            cout << search->data << " ";
            search = search->next;
        }
        cout << search->data << endl;
    };

};



int main()
{
    ll n = 0; 
    node* head = new node;
    while(1)
    {
        cin >> n;
        if(n == -1)
            break;
        head->append(n);
    }
    //head->print();
    while(1)
    {
        cin >> n;
        if(n == -1)
        break;
        if(!head->del(n))
        cout << "-1"<<endl;

        //head->print();
    }
    head->print();

}