/**
 * 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> largestValues(TreeNode* root) {
        vector<int> result;
        TreeNode* node ;
        queue<TreeNode*> my_que; 
        if(root == nullptr) return result;
        else 
        {
            my_que.push(root);
        }
        while(my_que.empty() != 1)
        {
            int size = my_que.size();
            int num = 0;  
            for(int i=0 ; i<size ; i++) 
            {
                node = my_que.front(); 
                my_que.pop();
                if(i==0)num = node->val;
                if(node->val > num) num = node->val;
                if(node->left != nullptr)    my_que.push(node->left);
                if(node->right != nullptr)   my_que.push(node->right);
            }
            result.push_back(num);
        }
        return result;
    }
};