1class TreeNode {
2    int val;
3    TreeNode left;
4    TreeNode right;
5    TreeNode() {}
6    TreeNode(int val) { this.val = val; }
7    TreeNode(int val, TreeNode left, TreeNode right) {
8        this.val = val;
9        this.left = left;
10        this.right = right;
11    }
12}
13
14class Solution {
15    private int dfs(TreeNode node, int maxVal) {
16        if (node == null) return 0;
17        int count = 0;
18        if (node.val >= maxVal) count = 1;
19        maxVal = Math.max(maxVal, node.val);
20        count += dfs(node.left, maxVal);
21        count += dfs(node.right, maxVal);
22        return count;
23    }
24
25    public int goodNodes(TreeNode root) {
26        return dfs(root, root.val);
27    }
28}
29

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;
    }
}