* Definition for a binary tree node.
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
vector<int> rightSideView(TreeNode* root) {
auto ret = vector<int>();
if (root == nullptr) return ret;
auto q = queue<const TreeNode*>();
for (auto i = 0; i < sz; ++i) {
if (n->left != nullptr ) q.push(n->left);
if (n->right != nullptr ) q.push(n->right);
if (i == sz - 1) ret.push_back(n->val);