/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    vector<int> LevelDis(TreeNode* root) {
        vector<TreeNode*> ret;
        vector<int> Ret;
        ret.push_back(root);
        while (!ret.empty()) {
            Ret.push_back(ret[ret.size()-1]->val);
            vector<TreeNode*> t;
            for (int i = 0; i < ret.size(); i++) {
                if (ret[i]->left != nullptr)
                    t.push_back(ret[i]->left);
                if (ret[i]->right != nullptr)
                    t.push_back(ret[i]->right);
            }
            ret = t;
        }
        return Ret;
    }
    vector<int> rightSideView(TreeNode* root) {
        vector<int> ret;
        if (root == nullptr) return ret;
        return LevelDis(root);
    }
};