1 #include<iostream>
  2 using namespace std;
  3 
  4 class Node {
  5 public:
  6     int data;
  7     Node *next;
  8     Node(int da):
  9         data(da), next(NULL){}
 10 };
 11 
 12 class List{
 13 private:
 14     Node *head;
 15 public:
 16     List(): head(NULL){}
 17     ~List(){
 18         delete head;
 19         cout<<"The list is deleted."<<endl;
 20     };
 21     int size(); // 链表长度
 22     bool isEmpty(); // 是否为空
 23     void printList(); // 打印链表
 24     void insert(int position, int value); // 指定位置插入
 25     void insertHead(int value); // 插入到最前
 26     void insertTail(int value); // 插入到最后
 27     int getValue(int position); // 查找指定位置的值
 28     int search(int value); // 查找指定元素的位置
 29     void update(int position, int value); // 更新指定位置的值
 30     int erase(int position); // 删除指定位置的节点
 31     void reverse(); // 反转链表
 32     //void clearList() // 清空链表
 33 };
 34 
 35 // 返回链表大小
 36 int List::size(){
 37     Node *p = head;
 38     int index = 0;
 39     while(p != NULL){
 40         index++;
 41         p = p->next;
 42     }
 43     return index;
 44 }
 45 
 46 // 判断链表是否为空
 47 bool List::isEmpty(){
 48     if(List::size() == 0)
 49         return true;
 50     else
 51         return false;
 52 }
 53 
 54 // 打印链表
 55 void List::printList(){
 56     Node *p = head;
 57     while(p != NULL){
 58         cout<<p->data<<" ";
 59         p = p->next;
 60     }
 61     cout<<endl;
 62     cout<<endl;
 63 }
 64 
 65 // 在position位置插入value
 66 void List::insert(int position, int value){
 67     if(position<0 || position>List::size()){
 68         cout<<"position error, please check."<<endl;
 69         return ;
 70     }
 71     Node *s = new Node(value); // new node
 72     Node *p = head;
 73     if(head == NULL){ // isEmpty = true
 74         head = s;
 75     }
 76     else{ // isEmpty = false
 77         if(position == 0){
 78             s->next = p;
 79             head = s;
 80         }
 81         else{
 82             int index = 0;
 83             while(index != position-1){
 84                 p = p->next;
 85                 index++;
 86             }
 87             s->next = p->next;
 88             p->next = s;
 89         }
 90     }
 91     if (position == 0)
 92         cout<<"insert "<<value<<" at the first."<<endl;
 93     else if (position == List::size())
 94         cout<<"insert "<<value<<" at the tail."<<endl;
 95     else
 96         cout<<"insert "<<value<<" at position "<<position<<endl;
 97 }
 98 
 99 // 头部插入
100 void List::insertHead(int value){
101     List::insert(0, value);
102 }
103 
104 // 尾部插入
105 void List::insertTail(int value){
106     List::insert(List::size(), value);
107 }
108 
109 // 搜索数据value，并返回位置
110 int List::search(int value){
111     Node *p = head;
112     int index = 0;
113     while(p != NULL && p->data != value){
114         index++;
115         p = p->next;
116     }
117     if(p == NULL){
118         cout<<"the value is not in the list, please check."<<endl;
119         return -1;
120     }
121     else{
122         cout<<value<<" at position "<<index<<endl;
123         return index;
124     }
125 }
126 
127 // 将position位置的数据更新为value
128 void List::update(int position, int value){
129     if(position<0 || position>(List::size()-1)){
130         cout<<"position error, please check."<<endl;
131         return ;
132     }
133     Node *p = head;
134     int index = 0;
135     while(index != position){
136         p = p->next;
137         index++;
138     }
139     p->data = value;
140     cout<<"update "<<value<<" at position "<<position<<endl;
141 }
142 
143 // 删除position位置的数据，并返回
144 int List::erase(int position){
145     if(position<0 || position>(List::size()-1)){
146         cout<<"position error, please check."<<endl;
147         return -1;
148     }
149     int res = List::getValue(position);
150     Node *p = head;
151     int index = 0;
152     cout<<"erase data at position "<<position<<endl;
153     if(position == 0){
154         head = p->next;
155         return res;
156     }
157     else{
158         while(index != position-1){
159             p = p->next;
160             index++;
161         }
162         Node *temp = p->next;
163         p->next = temp->next;
164         return res;
165     }
166 }
167 
168 // 反转链表
169 void List::reverse(){
170     if (head == NULL || head->next == NULL)
171         return ;
172     Node *prev = head;
173     Node *cur = head->next;
174     Node *temp = head->next->next;
175     while(cur){
176         temp = cur->next;
177         cur->next = prev;
178         prev = cur;
179         cur = temp;
180     }
181     head->next = NULL; // 更新末尾元素的指针
182     head = prev; // 更新头结点
183     cout<<"reverse the list."<<endl;
184 }
185 
186 // 返回position位置的数据
187 int List::getValue(int position){
188     if(position<0 || position>(List::size()-1)){
189         cout<<"position error, please check."<<endl;
190         return -1;
191     }
192     Node *p = head;
193     int index = 0;
194     while(index != position){
195         p = p->next;
196         index++;
197     }
198     cout<<"position "<<position<<" is "<<p->data<<endl;
199     return p->data;
200 }
201 /*
202 void List::clearList(){
203     Node *p = head;
204     while(p){
205         Node *temp = p->next;
206         delete p;
207         p = temp;
208     }
209 }
210 */
211 int main() {
212     List l1;
213     l1.insertTail(6);l1.printList();
214     l1.insertHead(7);l1.printList();
215     l1.insert(1, 5);l1.printList();
216     l1.insert(0, 16);l1.printList();
217     l1.insert(2, 56);l1.printList();
218     l1.insert(0, 169);l1.printList();
219     l1.insert(6, 16);l1.printList();
220     l1.search(16);
221     l1.getValue(5);
222     l1.update(1, 666);l1.printList();
223     l1.erase(0);l1.printList();
224     l1.reverse(); l1.printList();
225     cout<<"The size of the list: "<<l1.size()<<endl;
226     return 0;
227 }