/**
 * 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:
    vector<int> reverseBookList(ListNode* head) {
        recur(head);
        return res;
    }
private:
    vector<int> res;
    void recur(ListNode* cur) {
        if (cur == nullptr) return ;        // 终止条件
        recur(cur->next); // 递归后继节点
        res.push_back(cur->val);
    }
};