c++实现链表的建立、头插法、尾插法、删除指定节点、打印节点

#include <stdlib.h>
#include<iostream>
using namespace std;
//Definition for singly - linked list.
class Node {
public:
    int val;
    Node* next;
    Node() : val(0), next(nullptr) {}
    Node(int x) : val(x), next(nullptr) {}
    Node(int x, Node* next) : val(x), next(next) {}

    //创建链表 头结点
    static Node* createList(){
        Node* headNode = new Node;
        headNode->val = -1;
        headNode->next = nullptr;
        return headNode;
    }

    //创建节点
    static Node* creatNode(int data){
        Node* node = new Node;
        node->val = data;
        node->next = nullptr;
        return node;
    }

    //头插法
    void static insertNodeInHead(Node* list, int data) {
        Node* newNode;
        newNode = creatNode(data);
        newNode->next = list->next;
        list->next = newNode;
    }

    //尾插法
    void static insertNodeInEnd(Node* list, int data) {
        //没有第一个元素 就直接把list的next指向新节点
        if (list->next == nullptr) {
            list->next = creatNode(data);
            return;
        }
        //每次操作必须使用代理指针！！
        Node* p = list->next;
        while (p->next) {//不能判断p 因为要知道上一个有效节点
            p = p->next;
        }
        p->next = creatNode(data);
    }

    /**
    * 删除指定数据节点
    * 双指针 删除 pre是p的前一个指针
    * 要判断是否为空
    */
    void static deleteNode(Node* list, int data) {
        Node* p = list->next;//从头结点开始
        Node* pre = list;//p的前一个节点
        if (p == NULL) {
            cout << "this List is NULL "<< endl;
            return;
        }
        while (p) {//头结点的下一个节点
            if (p->val == data) {
                pre->next = p->next;
                free(p);
                cout<<"delete "<<data<<" successful！"<<endl;
                return;//若删除多个相同data节点  可以删除该句子和最后的 dont find
            }
            pre = pre->next;
            p = pre->next;//p一定 指向的是pre的下一个(这样可以保证 如果是多个节点的话）
        }
        cout<<"dont find this data:"<<data<<endl;
    }

    /**
     * 打印链表
     * 判断是否为空
     * @param list
     */
    void static printList(Node* list) {
        if (list->next == nullptr) {
            cout << "this list is NULL" << endl;
            return;
        }
        Node* p = list->next;//跳过头指针
        while (p) {
            cout << p->val <<"  ";
            p = p->next;
        }
        cout << endl;
    }

};


void test01()
{
    Node* list;
    //Node::createList();
    list = Node::createList();

    Node::printList(list);
    Node::insertNodeInEnd(list, 4);
    Node::insertNodeInEnd(list, 5);
    Node::insertNodeInEnd(list, 6);
    Node::insertNodeInHead(list, 3);
    Node::insertNodeInHead(list, 2);
    Node::insertNodeInHead(list, 1);
    //打印插入的所有
    Node::printList(list);
    //删除4
    Node::deleteNode(list, 4);
    Node::printList(list);

    Node::deleteNode(list, 4);
    Node::printList(list);
}


int main() {
    test01();
    return 0;
}