/**

 * Definition for a binary tree node.

 * struct TreeNode {

 *     int val;

 *     TreeNode *left;

 *     TreeNode *right;

 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}

 * };

 */

class Solution {

public:

    vector<vector<int>> levelOrderBottom(TreeNode* root) {

        vector< vector<int> > result;

        if (root == NULL)

            return result;

        queue<TreeNode*> q;

        q.push(root);

        while(!q.empty()) {

            int len = q.size();

            vector<int> temp;

            for (int i = ; i < len; ++i) {

                TreeNode* node = q.front();

                q.pop();

                temp.push_back(node->val);

                if(node->left != NULL)

                    q.push(node->left);

                if(node->right != NULL)

                    q.push(node->right);

            }

            result.insert(result.begin(), temp);

        }

        return result;

    }

};