bottom up level order travesal

/**
 * 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) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        vector<vector<int> > result;
    if(root==NULL)
		return result;
	queue<TreeNode*> curLevel;
	curLevel.push(root);
	while(!curLevel.empty()){
		vector<int> valLevel;
		int size = curLevel.size();
		for(int i=0;i<size;i++){
			TreeNode* node=curLevel.front();
			valLevel.push_back(node->val);
			if(node->left!=NULL)
				curLevel.push(node->left);
			if(node->right!=NULL)
				curLevel.push(node->right);
			curLevel.pop();
		}
		result.insert(result.begin(),valLevel);
	}
	return result;
    }
};