题解 | #判断一个链表是否为回文结构#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
//快慢指针，慢指针移动同时反转链表，当快指针到达终点后比较前后两个链表节点值是否一致
class Solution {
public:
    /**
     * 
     * @param head ListNode类 the head
     * @return bool布尔型
     */
    bool isPail(ListNode* head) {
        if(head == nullptr || head->next == nullptr){
            return true;
        }
        ListNode *pre = nullptr;
        ListNode *slow = head;
        ListNode *fast = head;
        while(fast && fast->next){
            fast = fast->next->next;
            ListNode *temp = slow->next;
            slow->next = pre;
            pre = slow;
            slow = temp;
        }
        //节点个数为奇数
        if(fast){
            return isequal(pre, slow->next);
        }else{
            return isequal(pre, slow);
        }
    }
    bool isequal(ListNode* head, ListNode *mid){
        while(head && mid){
            if(head->val != mid->val){
                return false;
            }
            head = head->next;
            mid = mid->next;
        }
        return true;
    }
};

class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!"); 
    }
}

print('Hello world!')