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

题解

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