C++ 解法, 执行用时: 13ms, 内存消耗: 5748KB, 提交时间: 2021-09-12

// *
//  * struct ListNode {
//  *	int val;
//  *	struct ListNode *next;
//  * };

static int x = []{
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    return 0;
}();
class Solution {
public:
    /**
     * 
     * @param head ListNode类 the head
     * @return bool布尔型
     */
    bool isPail(ListNode* head) {
        // write code here
        ListNode* slow = head;
        ListNode* fast = head;
        if(!fast->next)    return true;
        while(fast&&fast->next)
        {
            slow=slow->next;
            fast=fast->next->next;
        }
        if(fast)    slow= slow->next;
        ListNode* tmp = reverse(slow);
        while(head && tmp)
        {
            if(head->val != tmp->val)    return false;
            head=head->next;
            tmp=tmp->next;
        }
        return true;
    }
    ListNode* reverse(ListNode* root)
    {
        if(!root)    return root;
        ListNode* res = nullptr;
        ListNode* pre = root;
        while(root)
        {
            pre = root;
            root=root->next;
            pre->next = res;
            res=pre;
        }
        return res;
    }
};

C++ 解法, 执行用时: 13ms, 内存消耗: 6196KB, 提交时间: 2021-11-11

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
static int x = []{
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    return 0;
}();
class Solution {
public:
    /**
     * 
     * @param head ListNode类 the head
     * @return bool布尔型
     */
    bool isPail(ListNode* head) {
        // write code here
        if(!head || !head->next) return true;
        vector<int> temp;
        while(head) {
            temp.push_back(head->val);
            head = head->next;
        }
        int j = temp.size()-1;
        int i = 0;
        while(i < j){
            if(temp[i++] != temp[j--]) return false;
        }
        return true;
    }
};

C++ 解法, 执行用时: 14ms, 内存消耗: 5720KB, 提交时间: 2021-08-04

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
static int x = []{
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    return 0;
}();
class Solution {
public:
    /**
     * 
     * @param head ListNode类 the head
     * @return bool布尔型
     */
    bool isPail(ListNode* head) {
        // write code here
        if(!head || !head->next) return true;
        ListNode *fast = head, *slow = head;
        
        while(fast && fast->next)
        {
            fast = fast->next->next;
            slow = slow->next;
        }
        fast = slow->next;
        slow->next = nullptr;
        ListNode *newList = nullptr;
        
        while(fast)
        {
            newList = fast->next;
            fast->next = slow;
            slow = fast;
            fast = newList;
        }
        newList = slow;
        fast = head;
        while(fast && newList)
        {
            if(fast->val != newList->val) return false;
            fast = fast->next;
            newList = newList->next;
        }
        return true;
    }
};

C++ 解法, 执行用时: 14ms, 内存消耗: 6272KB, 提交时间: 2021-06-22

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param head ListNode类 the head
     * @return bool布尔型
     */
    bool isPail(ListNode* head) {
        // write code here
        if(head == nullptr || head->next == nullptr)
        {
            return true;
        }
        vector<int> tmp;
        while(head)
        {
            tmp.push_back(head->val);
            head = head->next;
        }
        int left = 0;
        int right = tmp.size() - 1;
        while(left < right)
        {
            if(tmp[left] != tmp[right])
            {
                return false;
            }
            left++;
            right--;
        }
        return true;
    }
};
static const auto io_sync_off = []()//lambda函数
{
    // turn off sync，关闭输入输出流的缓存
    std::ios::sync_with_stdio(false);
    // untie in/out streams，实现输入和输出流的解绑
    std::cin.tie(nullptr);
    return nullptr;
}();

C++ 解法, 执行用时: 15ms, 内存消耗: 5652KB, 提交时间: 2021-08-30

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
static int x = []{
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    return 0;
}();
class Solution {
public:
    /**
     * 
     * @param head ListNode类 the head
     * @return bool布尔型
     */
    bool isPail(ListNode* head) {
        // write code here
        if(!head || !head->next) return true;
        ListNode *fast = head, *slow = head;
        
        while(fast && fast->next)
        {
            fast = fast->next->next;
            slow = slow->next;
        }
        fast = slow->next;
        slow->next = nullptr;
        ListNode *newList = nullptr;
        while(fast)
        {
            newList = fast->next;
            fast->next = slow;
            slow = fast;
            fast = newList;
        }
        newList = slow;
        fast = head;
        while(fast && newList)
        {
            if(fast->val != newList->val) return false;
            fast = fast->next;
            newList = newList->next;
        }
        return true;
    }
};