c++学习-创建链表_c++创建链表

#include <iostream>
#include <vector>
using namespace std;
 
class MyLinkedList {
public:
    struct ListNode {
        int val;
        ListNode* next;
        ListNode(int x) : val(x), next(nullptr) {}
    };
 
    MyLinkedList() {
        size = 0;
        dummyhead = new ListNode(0);
    }
    
    int get(int index) {
        if (index < 0 || index >= size) {
            return -1;
        }
        ListNode *cur = dummyhead->next;
        for (int i = 0; i < index; i++) {
            cur = cur->next;
        }
        return cur->val;
    }
    
    void addAtHead(int val) {
        addAtIndex(0, val);
    }
    
    void addAtTail(int val) {
        addAtIndex(size, val);
    }
    
    void addAtIndex(int index, int val) {
        if (index > size) {
            return;
        }
        index = max(0, index);
        size++;
        ListNode *pred = dummyhead;
        for (int i = 0; i < index; i++) {
            pred = pred->next;
        }
        ListNode *toAdd = new ListNode(val);
        toAdd->next = pred->next;
        pred->next = toAdd;
    }
    
    void deleteAtIndex(int index) {
        if (index < 0 || index >= size) {
            return;
        }
        size--;
        ListNode *pred = dummyhead;
        for (int i = 0; i < index; i++) {
            pred = pred->next;
        }
        ListNode *toDelete = pred->next;
        pred->next = pred->next->next;
        delete toDelete;
    }
 
private:
    int size;
    ListNode *dummyhead;
};
 
 
int main() {
    MyLinkedList linkedList;  // 创建链表对象
 
    // 使用 addAtTail 方法添加元素
    linkedList.addAtTail(1);
    linkedList.addAtTail(2);
    linkedList.addAtTail(3);
    linkedList.addAtTail(4);
    linkedList.addAtTail(5);
    linkedList.addAtTail(6);
 
    // 打印链表来检查元素
    for (int i = 0; i < 6; i++) {
        cout << linkedList.get(i) << ' ';
        
    }
    cout <<endl;
 
    // 测试其他功能，例如删除和在头部添加
    linkedList.deleteAtIndex(3);  // 删除索引3的元素，即数字4
    linkedList.addAtHead(0);      // 在头部添加0
    
    for (int i = 0; i < 6; i++) {
        cout << linkedList.get(i) << ' ';
        
    }
    cout <<endl;
 
    return 0;
}