Count Good Nodes in Binary Tree

/**
 * 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:
    int goodNodes(TreeNode* root,int mx=INT_MIN) {

        if(!root)
        {
            return 0;
        }

        return (mx<=root->val?1:0)+goodNodes(root->left,max(root->val,mx))+goodNodes(root->right,max(root->val,mx));

    }
};