2023.9.5

        先将链表中的节点存储到数组中，再利用双指针重新构造符合条件的链表。代码如下：

/*** Definition for singly-linked list.* struct ListNode {*     int val;*     ListNode *next;*     ListNode() : val(0), next(nullptr) {}*     ListNode(int x) : val(x), next(nullptr) {}*     ListNode(int x, ListNode *next) : val(x), next(next) {}* };*/
class Solution {
public:void reorderList(ListNode* head) {vector<ListNode*> v;ListNode* cur = head;while(cur){v.push_back(cur);cur = cur->next;}cur = head;int left = 1;int right = v.size()-1;int num = 0;while(left <= right){if(num % 2 == 0){cur->next = v[right];cur = cur->next;num++;right--;}else{cur->next = v[left];cur = cur->next;num++;left++;}}cur->next = nullptr;}
};