234_palindromelinkedlist.cpp

class Solution {
public:
    bool isPalindrome(ListNode* head) {
        if (head == nullptr || head->next == nullptr) {
            return true; 
        }

        ListNode* slow = head;
        ListNode* fast = head;

        while (fast != nullptr && fast->next != nullptr) {
            slow = slow->next;
            fast = fast->next->next;
        }

        ListNode* reversed = reverseList(slow);
        ListNode* curr = head;

        while (reversed != nullptr) {
            if (curr->val != reversed->val) {
                return false; // Not a palindrome
            }
            curr = curr->next;
            reversed = reversed->next;
        }

        return true; // Palindrome
    }

private:
    ListNode* reverseList(ListNode* head) {
        ListNode* prev = nullptr;
        ListNode* curr = head;

        while (curr != nullptr) {
            ListNode* nextNode = curr->next;
            curr->next = prev;
            prev = curr;
            curr = nextNode;
        }

        return prev;
    }
};