1class TreeNode:
2    def __init__(self, val=0, left=None, right=None):
3        self.val = val
4        self.left = left
5        self.right = right
6
7class Solution:
8    def dfs(self, node, maxVal):
9        if not node:
10            return 0
11        good = 1 if node.val >= maxVal else 0
12        maxVal = max(maxVal, node.val)
13        return good + self.dfs(node.left, maxVal) + self.dfs(node.right, maxVal)
14
15    def goodNodes(self, root):
16        return self.dfs(root, root.val)
17

using System.Collections.Generic;

public class TreeNode {
    public int val;
    public TreeNode left;
    public TreeNode right;
    public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
        this.val = val;
        this.left = left;
        this.right = right;
    }
}

public class Solution {
    public int GoodNodes(TreeNode root) {
        if (root == null) return 0;
        Queue<(TreeNode, int)> queue = new Queue<(TreeNode, int)>();
        queue.Enqueue((root, root.val));
        int goodCount = 0;
        while (queue.Count > 0) {
            (TreeNode node, int maxVal) = queue.Dequeue();
            if (node.val >= maxVal) goodCount++;
            if (node.left != null) queue.Enqueue((node.left, Math.Max(maxVal, node.val)));
            if (node.right != null) queue.Enqueue((node.right, Math.Max(maxVal, node.val)));
        }
        return goodCount;
    }
}