LeetCode (Binary Tree Right Side View)

Problem:

Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.

For example:
Given the following binary tree,

   1            <--- /   \2     3         <--- \     \  5     4       <---

You should return [1, 3, 4].

Solution:

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    vector<int> rightSideView(TreeNode* root) {        vector<int> ans;        if(!root) return ans;        vector<int> right = rightSideView(root->right);        vector<int> left = rightSideView(root->left);        ans.push_back(root->val);        for(auto n : right)            ans.push_back(n);        for(int i = right.size(); i < left.size(); i++)            ans.push_back(left[i]);        return ans;    }};