/**

* 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>> levelOrder(TreeNode* root) {

vector<vector<int>> res;

if (root == NULL)

return res;

queue<TreeNode*> qNodes;

vector<int> cur;

qNodes.push(root);

qNodes.push(NULL);

while (!qNodes.empty())

{

TreeNode* tmp = qNodes.front();

qNodes.pop();

if (tmp == NULL)

{

res.push_back(cur);

cur.resize(0);

if (qNodes.size() > 0)

qNodes.push(NULL);

}

else

{

cur.push_back(tmp->val);

if (tmp->left)

qNodes.push(tmp->left);

if (tmp->right)

qNodes.push(tmp->right);

}

}

return res;

}

};