1public class TreeNode {
2    public int val;
3    public TreeNode left;
4    public TreeNode right;
5    public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
6        this.val = val;
7        this.left = left;
8        this.right = right;
9    }
10}
11
12public class Solution {
13    private int Dfs(TreeNode node, int maxVal) {
14        if (node == null) return 0;
15        int good = (node.val >= maxVal) ? 1 : 0;
16        maxVal = Math.Max(maxVal, node.val);
17        good += Dfs(node.left, maxVal);
18        good += Dfs(node.right, maxVal);
19        return good;
20    }
21
22    public int GoodNodes(TreeNode root) {
23        return Dfs(root, root.val);
24    }
25}
26

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;
    }
}