/**

* Definition for binary tree

* 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) {

if (!root) {return vector<vector<int> >();}

vector<pair<TreeNode*,int> > q;

int lev=1;

int count=0;

q.push_back(make_pair(root,lev));

while (count<q.size()){

TreeNode *node = q[count].first;

lev = q[count].second;

if (node->left){ q.push_back(make_pair(node->left,lev+1));}

if (node->right){ q.push_back(make_pair(node->right,lev+1));}

count++;

}

vector<vector<int> > res(lev, vector<int>());

for (int i=0;i<q.size();i++){

res[lev-q[i].second].push_back(q[i].first->val);

}

return res;

}

};