/**
 * 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> findMode(TreeNode* root) {
        result.clear();
        m.clear();
        most=0;
        if(root==nullptr)
            return result;

        t(root);
        for(auto&& p:m)
        {
            if(p.second==most)
                result.push_back(p.first);
        }
        return result;
    }

    void t(TreeNode* node)
    {
        if(node==nullptr)
            return;
        ++m[node->val];
        most=max(most,m[node->val]);
        t(node->left);
        t(node->right);
    }
    vector<int> result;
    int most;
    unordered_map<int,int> m;
};