先遍历链表,然后翻转

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    vector<int> printListReversingly(ListNode* head) {
        vector<int> a;
        while(head!=NULL){
            a.push_back(head->val);
            head=head->next;
        }
        reverse(a.begin(), a.end());    
        return a;
    }
};

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    vector<int> printListReversingly(ListNode* head) {
        vector<int> a;
        while(head!=NULL){
            a.push_back(head->val);
            head=head->next;
        }
        return vector<int>(a.rbegin(), a.rend());   
        //rbegin()返回一个逆序迭代器，它指向容器c的最后一个元素;c.rend() //返回一个逆序迭代器，它指向容器c的第一个元素前面的位置

    }
};