链表反转

就直接贴代码了：

#include <iostream>
#include <ctime>
#include <cstdlib>
using namespace std;

#define NN 1

struct node
{
 int value;
 node * next;
 node(int v = -1, node *nxt = NULL) : value(v),next(nxt){}
};

node* reverse(node * ); //直接使用 node 代表这个结构体
node * make_link();
void display(node *);

int main()
{

 node* head = make_link();
 display(head);
 head = reverse(head);
 display(head);
 return 0;
}

node* reverse(node *head)
{
 node *pre, *cur, *post;
 if(!head || !head->next)//空表或者只有一个节点的表不用反转
  return head;

 pre = head;       ///除了头还需要另外两个辅助变量
 cur = pre->next;

 while(cur)
 {
  post = cur->next;
  cur->next = pre;
  pre = cur;
  cur = post;
 }
 head->next = NULL;
 return pre;
}
node * make_link()
{
 srand(time(NULL));
 node *head = new node();
 node *cur = head;
 for(int i= 0; i < 9; i++)
 {
  cur->value =  rand() % 10;
  cur->next = new node();
  cur = cur->next;
  cur->next = NULL;
 }
    cur->value = rand() % 10;
 return head;
}
void display(node *head)
{
 node *cur = head;
 int Nodenum = 0;
 while(cur)
 {
  cout << cur->value << " " ;//<< cur->next<<" \n ";
        Nodenum++;
  cur = cur->next;
 }
 cout << endl;
#ifdef NN
 cout << Nodenum<<endl;
#endif
}