1#include <iostream>
2
3class MyLinkedList {
4private:
5    struct Node {
6        int val;
7        Node* next;
8        Node(int _val) : val(_val), next(nullptr) {}
9    };
10    Node* head;
11
12public:
13    MyLinkedList() : head(nullptr) {}
14
15    int get(int index) {
16        Node* current = head;
17        for (int i = 0; current && i < index; ++i) {
18            current = current->next;
19        }
20        return current ? current->val : -1;
21    }
22
23    void addAtHead(int val) {
24        Node* node = new Node(val);
25        node->next = head;
26        head = node;
27    }
28
29    void addAtTail(int val) {
30        Node* node = new Node(val);
31        if (!head) {
32            head = node;
33        } else {
34            Node* current = head;
35            while (current->next) {
36                current = current->next;
37            }
38            current->next = node;
39        }
40    }
41
42    void addAtIndex(int index, int val) {
43        if (index == 0) {
44            addAtHead(val);
45            return;
46        }
47        Node* current = head;
48        for (int i = 0; current && i < index - 1; ++i) {
49            current = current->next;
50        }
51        if (current) {
52            Node* node = new Node(val);
53            node->next = current->next;
54            current->next = node;
55        }
56    }
57
58    void deleteAtIndex(int index) {
59        if (index == 0 && head) {
60            Node* temp = head;
61            head = head->next;
62            delete temp;
63            return;
64        }
65        Node* current = head;
66        for (int i = 0; current && i < index - 1; ++i) {
67            current = current->next;
68        }
69        if (current && current->next) {
70            Node* temp = current->next;
71            current->next = current->next->next;
72            delete temp;
73        }
74    }
75};

1