倒序打印链表

递归实现

class Solution {
private:
    vector<int> result;
public:
    vector<int> printListFromTailToHead(ListNode* head) {
        if(head != NULL)
        {
            if(head->next!=NULL)
            {
                printListFromTailToHead(head->next);
            }
            result.push_back(head->val);
        }
        return result;
    }
};

借助栈实现

class Solution {
public:
    vector<int> printListFromTailToHead(ListNode* head) {
        ListNode *pnode = head;
        vector<int> result;
        stack<int> myresult;
        while(pnode!=NULL)
        {
            myresult.push(pnode->val);
            pnode=pnode->next;
        }
        while(!myresult.empty())
        {
            result.push_back(myresult.top());
            myresult.pop();
        }
        return result;
    }
};