数据结构与算法-----单向线性链表（逆转和反向打印）

// 练习：实现单向线性链表的建立、测长、正向打印和
// 反向打印
// 逆转
#include <iostream>
using namespace std;
class List {
public:
// 构造函数中初始化为空链表
List (void) : m_head (NULL), m_tail (NULL) {}
// 析构函数中销毁剩余的节点
~List (void) {
for (Node* next; m_head; m_head = next) {
next = m_head -> m_next;
delete m_head;
}
}
// 追加
void append (int data) {
Node* node = new Node (data);
if (m_tail)
m_tail -> m_next = node;
else
m_head = node;
m_tail = node;
}
// 测长
size_t length (void) const {
size_t len = 0;
for (Node* node = m_head; node;
node = node -> m_next)
len++;
return len;
}
// 正向打印
void print (void) const {
for (Node* node = m_head; node;
node = node -> m_next)
cout << node -> m_data << ' ';
cout << endl;
}
// 反向打印
void rprint (void) const {
rprint (m_head);
cout << endl;
}
//逆转
void reverse(void){
reverse(m_head);
swap(m_head,m_tail);
}
private:
// 节点
class Node {
public:
Node (int data = 0, Node* next = NULL) :
m_data (data), m_next (next) {}
int   m_data; // 数据
Node* m_next; // 后指针
};
// 反向打印以head为首的子链表
void rprint (Node* head) const {
if (head) {//使用递归（也即堆栈方式）实现逆向打印链表
rprint (head -> m_next);
cout << head -> m_data << ' ';
}//如果head为空，函数会一层一层的返回
}
void reverse(Node *head){
if(head && head->m_next){
reverse(head->m_next);
head->m_next->m_next=head;
head->m_next=NULL;
}
}
Node* m_head; // 头指针
Node* m_tail; // 尾指针
};
int main (void) {
List list;
for (int i = 1; i <= 20; i++)
list.append (i);
cout << list.length () << endl;
list.print ();
list.rprint ();
list.reverse ();
list.print ();
return 0;
}