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

    1. //24 ms    11.3 MB
    3. /**
    4.  * Definition for singly-linked list.
    5.  * struct ListNode {
    6.  *     int val;
    7.  *     ListNode *next;
    8.  *     ListNode(int x) : val(x), next(NULL) {}
    9.  * };
    10.  */
    11. class Solution {
    12. public:
    13.     bool isPalindrome(ListNode* head) {
    14.         if(!head || !head->next) return true;
    16.         ListNode* tail = head;
    17.         while(tail->next->next){
    18.             tail = tail->next;
    19.         }
    21.         if(tail->next->val != head->val){
    22.             return false;
    23.         }
    25.         tail->next = NULL;
    27.         return true && isPalindrome(head->next);
    28.     }
    29. };
    /**
 * 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) {
        if(!head || !head->next) return true;

        vector<int> lst;
        ListNode* curr = head;

        while(curr){
            lst.push_back(curr->val);
            curr = curr->next;
        }

        int l = 0, r = lst.size()-1;
        while(l<=r){
            if(lst[l] != lst[r])
                return false;
            else{
                l++;
                r--;
            }
        }

        return true;
    }
};