/**
* 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> rightSideView(TreeNode* root) {
deque<TreeNode*> q;
q.push_back(root);
vector<int> res;
if(root==NULL) return res;
while(!q.empty()){
TreeNode* tmp =q.back();
res.push_back(tmp->val);
int s=q.size();
while(s--){
TreeNode* f=q.front();
q.pop_front();
if(f->left) q.push_back(f->left);
if(f->right) q.push_back(f->right);
}
}
return res;
}
};