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

Example:

Input:[1,2,3,null,5,null,4]
Output:[1, 3, 4]
Explanation:

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

class
 
 Solution {
public:
    vector<int> rightSideView(TreeNode* root) {
        
        vector<int> res;
        if (!root) return res;
        
        queue<TreeNode*> q;
        q.push(root);
        while (!q.empty()){
            int n = q.size();
            TreeNode* cur;
            
 
while (n){
                cur = q.front();
                q.pop();
                if(cur->left)
                    q.push(cur->left);
                if(cur->right)
                    q.push(cur->right);
                n--;
            }
            res.push_back(cur->val);
        }
        
        
 
return res;
        
    }
};