goodNodes.cpp

/**
 * 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:
    void dfs(TreeNode *root, int cur_max) {
        cur_max = std::max(cur_max, root->val);
        if (root->val == cur_max)
            ++count;
        
        if (root->left) dfs(root->left, cur_max);
        if (root->right) dfs(root->right, cur_max);
    }
    int goodNodes(TreeNode* root) {
        count = 0;
        dfs(root, INT_MIN);
        return count;
    }
private:
    int count;
};