第二个进入 2ms 的算法。很开心 ^_^

时间：2ms
内存：412KB

```c++
/**

  • struct TreeNode {
  • int val;
  • struct TreeNode *left;
  • struct TreeNode *right;
  • };
  • /

class Solution {
public:
/*
*
* @param root TreeNode类
* @return int整型vector<vector<>>
*/
vector<vector<int> > levelOrder(TreeNode</int> root) {
// write code here
queue<TreeNode> q;
q.push(root);
vector<vector<int>> results;
TreeNode</int> tmp;
while(q.size()){
vector<int> data;
for(int size = q.size(); size; --size){
tmp = q.front();
if(tmp){
data.push_back(tmp->val);
q.push(tmp->left);
q.push(tmp->right);
}
q.pop();</int>

        }
        if(data.size()) results.push_back(data);
    }
    return results;
}

};