/**
 * 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:

    map<int,int> m;

    vector<int> ans(){

        int maxi=0;
        for(auto i:m){
            maxi=max(maxi,i.second);
        }
        vector<int> ret;
        for(auto i:m){
            if(i.second==maxi){
                ret.push_back(i.first);
            }
        }

        return ret;

    }

    vector<int> findMode(TreeNode* root) {

        if(root==nullptr){
            return {};
        }
        m[root->val]++;

        findMode(root->left);
        findMode(root->right);


        return ans();
    }
};