Binary-Tree-Level-Order-Traversal-II.cpp

classSolution {
public:
 vector<vector<int>> ans;
voiddfs(int dep, TreeNode* root){
if (root == NULL) return;
while (dep >= ans.size()) ans.push_back(vector<int>());
 ans[dep].push_back(root->val);
dfs(dep + 1, root->left);
dfs(dep + 1, root->right);
 }
 vector<vector<int>> levelOrderBottom(TreeNode* root) {
dfs(0, root);
reverse(ans.begin(), ans.end());
return ans;
 }
};