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#include "leetcode.h"

class Solution {
public:
  bool isPalindrome(ListNode *head) {
    ListNode *slow = head, *fast = head, *prev, *temp;
    while (fast && fast->next) {
      slow = slow->next;
      fast = fast->next->next;
    }
    prev = slow;
    slow = slow->next;
    prev->next = NULL;
    while (slow) {
      temp = slow->next;
      slow->next = prev;
      prev = slow;
      slow = temp
    }
    fast = head;
    slow = prev;
    while (slow) {
      if (fast->val != slow->val)
        return false;
      else {
        fast = fast->next;
        slow = slow->next;
      }
    }
    return true;
  }
};