234. Palindrome Linked List .txt

https://leetcode.com/problems/palindrome-linked-list/

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
private: 
    ListNode* reverse = nullptr;
    ListNode* Rev(ListNode* head){
        if(!head->next){reverse = head;return head;}
        Rev(head->next)->next = head;
        head->next = nullptr;
        return head;
    }
public:
    bool isPalindrome(ListNode* headRoot) {
        if(!headRoot){return true;}
        ListNode* head = headRoot;
        ListNode* fast = headRoot;
        while(fast && fast->next){
            head = head->next;
            fast = fast->next->next;
        }
        Rev(head);
        while(reverse){
            //cout <<reverse->val <<"  "<< headRoot->val<<endl;
            if(reverse->val != headRoot->val){return false;}
            reverse = reverse->next;
            headRoot = headRoot->next;
        }
        return true;
    }
};