思路：主要是确定，虚拟头节点不算个数，从第一个正式节点开始计数，下标从0开始，这个确定了就写就完了
typedef struct Node // 定义节点
{int val;struct Node* next;
} Node;typedef struct MyLinkedList // 定义链表
{int size; // 链表中节点的数量Node* head; // 指向链表头结点的指针
} MyLinkedList;// 初始化 MyLinkedList
MyLinkedList* myLinkedListCreate()
{MyLinkedList* obj = (MyLinkedList*)malloc(sizeof(MyLinkedList)); // 定义一个空链表Node* dummyhead = (Node*)malloc(sizeof(Node)); // 定义一个空节点dummyhead->next = NULL;obj->head = dummyhead; // 头结点指向空节点obj->size = 0; // 设置链表节点数量为 0return obj;
}// 获取链表中下标为 index 的节点的值
int myLinkedListGet(MyLinkedList* obj, int index)
{if (index < 0 || index >= obj->size) // 索引超出范围return -1;Node* cur = obj->head->next; // 从头结点的下一个节点开始while (index--){cur = cur->next;}return cur->val;
}// 在头部插入节点
void myLinkedListAddAtHead(MyLinkedList* obj, int val)
{Node* newNode = (Node*)malloc(sizeof(Node)); // 分配新节点newNode->val = val;newNode->next = obj->head->next; // 新节点指向原头节点obj->head->next = newNode; // 头节点指向新节点obj->size++; // 更新链表大小
}// 在尾部插入节点
void myLinkedListAddAtTail(MyLinkedList* obj, int val)
{Node* newNode = (Node*)malloc(sizeof(Node));newNode->val = val;newNode->next = NULL;Node* cur = obj->head;while (cur->next != NULL) {cur = cur->next;}cur->next = newNode;obj->size++;
}// 在指定位置插入节点
void myLinkedListAddAtIndex(MyLinkedList* obj, int index, int val)
{if (index < 0 || index > obj->size) // 插入位置超出范围return;Node* newNode = (Node*)malloc(sizeof(Node));newNode->val = val;Node* cur = obj->head;while (index--){cur = cur->next;}newNode->next = cur->next;cur->next = newNode;obj->size++;
}// 删除指定位置节点
void myLinkedListDeleteAtIndex(MyLinkedList* obj, int index)
{if (index < 0 || index >= obj->size) // 索引超出范围return;Node* cur = obj->head;while (index--){cur = cur->next;}Node* toDelete = cur->next;cur->next = toDelete->next;free(toDelete);obj->size--;
}// 释放链表
void myLinkedListFree(MyLinkedList* obj)
{Node* cur = obj->head;while (cur != NULL) {Node* next = cur->next;free(cur);cur = next;}free(obj);
}
