以下是使用另一种方法实现该代码的单链表：
”`cpp #ifndef NULL #define NULL 0 #endif
#include
// 定义单链表结点结构 struct LNode {
int data;LNode* next;LNode() {};LNode(int e, LNode* n = NULL) : data(e), next(n) {};
};
// 单链表list类创建 class List { protected:
LNode* head;int _size;
public:
// 构造函数List() {head = new LNode;head->next = NULL;_size = 0;}// 析构函数~List() {while (head) {LNode* p = head->next;delete head;head = p;}}// 头节点List(int info) {head = new LNode(info);_size = 0;}int& info() { return head->data; } // 返回链表头结点的信息void insert(int& e) {_size++;LNode* p = new LNode(e);p->next = head->next;head->next = p;}void insert(int index, int a){if (index < 1 || index > _size + 1)return; // 无效的插入位置，直接返回_size++;LNode* tmp = new LNode(a);if (index == 1) {tmp->next = head->next;head->next= tmp;return;}LNode* pre = nullptr, * cur = head->next;int count = 1;while (count < index) {pre = cur;cur = cur->next;count++;}tmp->next = cur;pre->next = tmp;}void print_L() {LNode* p = head->next;while (p != NULL) {cout << p->data << " ";p = p->next;}cout << endl;}int change(){int x, y;cin >> x >> y;if (x < 0 || x > _size || y < 0 || y > _size){cout << "error" << endl;return -1;}if (x == y)return 0;LNode* px_prev = nullptr, * py_prev = nullptr, * px, * py;// 寻找第 x 个结点和它的前驱int count_x = 0;px_prev = head;while (count_x < x - 1) {px_prev = px_prev->next;count_x++;}px = px_prev->next;// 寻找第 y 个结点和它的前驱int count_y = 0;py_prev = head;while (count_y < y - 1) {py_prev= py_prev -> next;count_y++;}py= py_ prev -> next;// 进行交换操作LNode* temp=px- > next;//保存px之后的结点，以便于重新链接；px- > next= py- > next;py_prev -> next= px;py- > next=temp;px_ prev ->next = py;return 0;};
};
int main() {
List LB;int n, a;cin >> n;for (int i = 0; i < n; i++){cin >> a;LB.insert(i + 1, a);}LB.print_L();int t;cin >> t;for (int i = 0; i < t; i++){int a = LB.change();if (a == -1)continue;LB.print_L();}
}
“`
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