leetcode102

class Solution {
public:
    vector<vector<int>> levelOrder(TreeNode* root) {
        vector<vector<int>> res;
        queue<TreeNode*>q;                
        if (root != NULL)
        {
            q.push(root);
            while (!q.empty())
            {
                vector<int> tmp;
                vector<TreeNode*> T;
                while (!q.empty())
                {
                    TreeNode* t = q.front();
                    q.pop();
                    tmp.push_back(t->val);
                    if (t->left != NULL)
                    {
                        T.push_back(t->left);
                    }
                    if (t->right != NULL)
                    {
                        T.push_back(t->right);
                    }
                }                
                res.push_back(tmp);
                for (auto x : T)
                {
                    q.push(x);
                }
            }
        }
        return res;
    }
};