/**

  * Definition for singly-linked list.

  * struct ListNode {

  *     int val;

  *     ListNode *next;

  *     ListNode(int x) : val(x), next(NULL) {}

  * };

  */

 class Solution {

 public:

     bool isPalindrome(ListNode* head) {

         int ln = , i = ;

         ListNode* rhead = NULL;

         ListNode* now, *rnow;

         for(now = head; now; now = now->next, ++ln);

         for(now = head; i < ln / ; ++i){

             ListNode* tnow = now;

             now = now->next;

             tnow->next = rhead;

             rhead = tnow;

         }

         if(ln %  == ){

             now = now->next;

         }

         for(rnow = rhead; now && rnow; rnow = rnow->next, now = now->next){

             if(rnow->val != now->val) return false;

         }

         return true;

     }

 };