题解 | #重排链表#

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