剑指offer--18.从尾到头打印链表

/**
*  struct ListNode {
*        int val;
*        struct ListNode *next;
*        ListNode(int x) :
*              val(x), next(NULL) {
*        }
*  };
*/
class Solution {
public:
    vector<int> printListFromTailToHead(ListNode* head) {
        vector<int> vec;
        if(head != NULL) {
            if(head->next != NULL) {
                vec = printListFromTailToHead(head->next);
            }
            vec.push_back(head->val);
        }
        return vec;
    }
};