5-21打卡：双循环链表（无哨兵）练习

#include<iostream>
using namespace std;

typedef struct Node {
    int data;
    Node* next;
    Node* pre;
}Node;

Node* initlist(int data)
{
    Node* node = new Node;
    node->data = data;
    node->next = node;
    node->pre = node;
    return node;
}

void headinsert(Node*& head, int data)
{
    Node* node = new Node;
    node->data = data;

    node->next = head;
    node->pre = head->pre;
    head->pre->next = node;
    head->pre = node;
    head = node;
}

void tailinsert(Node* head, int data)
{
    Node* node = new Node;
    node->data = data;

    node->pre = head->pre;
    node->next = head;
    head->pre->next = node;
    head->pre = node;
}

void printlist(Node* head)
{
    Node* node = head->next;
    cout << head->data << "->";
    while (node != head)
    {
        cout << node->data << "->";
        node = node->next;
    }
    cout << "NULL" << endl;
}

void nodedelete(Node*& head, int data) 
{
    Node* node = head;
    if (node->data == data)
    {
        node->pre->next = node->next;
        node->next->pre = node->pre;
        head = node->next; 
    }
    node = node->next;

    while (node != head)
    {

        if (node->data == data)
        {
            node->pre->next = node->next;
            node->next->pre = node->pre;
        }
        node = node->next;
    }
}


int main()
{
    Node* a = initlist(5);
    headinsert(a, 4);
    headinsert(a, 3);
    headinsert(a, 2);
    headinsert(a, 1);
    headinsert(a, 0);
    tailinsert(a, 7);
    tailinsert(a, 8);
    tailinsert(a, 9);
    tailinsert(a, 10);
    tailinsert(a, 11);
    printlist(a);
    nodedelete(a, 10);
    nodedelete(a, 0);
    nodedelete(a, 11);
    nodedelete(a, 4);
    printlist(a);
    return 0;
}