C++实现链表插入删除查找

在C++中，链表是一种常见的数据结构，它由一系列节点组成，每个节点包含数据和指向下一个节点的指针。以下是基本的链表操作：

1. 插入元素：
- **在头部插入** (`insertAtBeginning`): 创建新节点并将其指针设置为头节点，然后将当前头节点的指针更新为新节点。

   struct Node {
       int data;
       Node* next;
   };
   
   void insertAtBeginning(Node*& head, int value) {
       Node* newNode = new Node{value, nullptr};
       newNode->next = head;
       head = newNode;
   }

- **在指定位置插入** (`insertAtPosition`): 需遍历找到目标位置，并调整后续节点的指针。

   void insertAtPosition(Node*& head, int position, int value) {
       if (position <= 0) return; // 非法位置处理
       Node* newNode = new Node{value, nullptr};
       Node* current = head;
       for (int i = 0; i < position - 1 && current != nullptr; ++i) {
           current = current->next;
       }
       newNode->next = current->next;
       if (current != nullptr) current->next = newNode;
   }

2. 删除元素：
- **删除头节点** (`removeHead`): 如果头节点存在，则更新头节点为第二个节点。

   void removeHead(Node*& head) {
       if (head != nullptr) {
           Node* temp = head;
           head = head->next;
           delete temp;
       } else {
           std::cout << "List is empty" << std::endl;
       }
   }

- **根据值删除** (`removeValue`): 遍历链表寻找特定值的节点并删除。

   void removeValue(Node*& head, int value) {
       while (head != nullptr && head->data == value) {
           Node* temp = head;
           head = head->next;
           delete temp;
       }
       Node* current = head;
       while (current != nullptr && current->next != nullptr) {
           if (current->next->data == value) {
               Node* toDelete = current->next;
               current->next = current->next->next;
               delete toDelete;
           } else {
               current = current->next;
           }
       }
   }

3. 查找元素：
- **线性查找** (`search`): 遍历整个链表直到找到匹配项或结束。

   bool search(Node* head, int value) {
       Node* current = head;
       while (current != nullptr) {
           if (current->data == value) return true;
           current = current->next;
       }
       return false;
   }