求链表的中心节点

#include<iostream>
using namespace std;

class node{
public:
    node():value(0),next(NULL){}
    ~node(){}
    int value;
    node* next;
};///be careful this ;

node* createlist(int a[],int n)
{
 node* startnode = new node[n];
 node* ret = startnode;
 for(int i = 0;i<n;i++)
 {
     startnode[i].value = a[i];
     if(i<n-1) 
         startnode[i].next = startnode + i + 1;
 }
 while(startnode)
 {
     cout<<" "<<startnode->value;
     startnode = startnode->next;
 }
 cout<<endl;
 return ret;
}

void helper(node* head)
{
  node* temp = head;
  while(head->next != NULL && head->next->next != NULL)
  {
      head = head->next->next;
      temp = temp->next;
  }
  cout<<temp->value; ///如果是奇数个，就是中间，如果是偶数个，指向第一个
}

int main()
{
    int a[] = {1,2,3,4,5,6,7,8,9};
    node * t = createlist(a,8);
    helper(t);

}