从尾到头输出链表

输入一个链表，按链表值从尾到头的顺序返回一个ArrayList。

/**
*  struct ListNode {
*        int val;
*        struct ListNode *next;
*        ListNode(int x) :
*              val(x), next(NULL) {
*        }
*  };
*/
class Solution {
public:
    vector<int> printListFromTailToHead(ListNode* head) {
        vector<int> ret;
        if (head == NULL) return ret;
        //反转链表
        ListNode d(-1);
        ListNode* dummy = &d;
        for (;head != NULL;) {
            ListNode* tmp = head->next;
            head->next = dummy->next;
            dummy->next = head;
            head = tmp;
        }
        
        for (;dummy->next != NULL;) {
            ret.push_back(dummy->next->val);
            dummy = dummy->next;
        }
        return ret;
    }
};