Palindrome Linked List leetcode

Given a singly linked list, determine if it is a palindrome.

Follow up:
Could you do it in O(n) time and O(1) space?

 

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思路：

1.利用快慢两个指针找到中间结点

2.从中间结点下一个结点开始逆置链表，得到新的链表

3.新的链表与原来链表依次比较结点，如有不同，return false

 

思路很清晰，代码直接写在leetcode网站上了，没有调试，一次性AC通过，很有成就感

bool isPalindrome(ListNode* head) {
    if (head == nullptr || head->next == nullptr)
        return true;
    // 寻找中间结点
    ListNode *slow = head;
    ListNode *fast = head;
    while (fast->next != nullptr && fast->next->next != nullptr)
    {
        slow = slow->next;
        fast = fast->next->next;
    }
    // 逆置后部分链表
    ListNode *newList = slow->next;
    ListNode *curNode = slow->next->next;
    newList->next = nullptr;
    while (curNode != nullptr)
    {
        ListNode *temp = curNode->next;
        curNode->next = newList;
        newList = curNode;
        curNode = temp;
    }
    // 依次比较
    while (newList != nullptr)
    {
        if (newList->val != head->val)
            return false;
        newList = newList->next;
        head = head->next;
    }
    return true;
}