lintcode 二叉树的锯齿形层次遍历

二叉树的锯齿形层次遍历

描述：

给出一棵二叉树，返回其节点值的锯齿形层次遍历（先从左往右，下一层再从右往左，层与层之间交替进行） 

您在真实的面试中是否遇到过这个题？ 

Yes

样例

给出一棵二叉树 {3,9,20,#,#,15,7},

    3
   / 
  9  20
    /  
   15   7

返回其锯齿形的层次遍历为：

[
  [3],
  [20,9],
  [15,7]
]
代码
（不知道为什么vector中的翻转reverse用不了，提交时会出现编译错误
In file included from /code/Main.cpp:23:0:
/code/Solution.cpp: In member function 'std::vector<std::vector > Solution::zigzagLevelOrder(TreeNode*)':
/code/Solution.cpp:30:22: error: 'class std::vector' has no member named 'reverse'
base.reverse(base.begin(), base.end()); 
）

class Solution {
public:
    /*
     * @param root: A Tree
     * @return: A list of lists of integer include the zigzag level order traversal of its nodes' values.
     */
    vector<vector<int>> zigzagLevelOrder(TreeNode * root) {
        // write your code here
        vector<vector<int>> res;
        if (root == NULL) return res;
        bool flag = false;
        queue<TreeNode*> que;
        que.push(root);

        while (!que.empty()) {
            int count = que.size();
            vector<int> base;
            while (count--) {
                TreeNode *temp = que.front();
                que.pop();
                base.push_back(temp->val);
                if (temp->left) {
                    que.push(temp->left);
                }
                if (temp->right) {
                    que.push(temp->right);
                }
            }
            if (flag) {
                vector<int> t;
                for (int i = base.size() - 1; i >= 0; i--) {
                    t.push_back(base[i]);
                }
                res.push_back(t);
            } else {
                res.push_back(base);
            }
            flag = !flag;
        }
        return res;
    }
};