Count Good Nodes in Binary Tree

Given a binary tree root, a node X in the tree is named good if in the path from root to X there are no nodes with a value greater than X.

Return the number of good nodes in the binary tree.

Example 1:

Input: root = [3,1,4,3,null,1,5]
Output: 4
Explanation: Nodes in blue are good.
Root Node (3) is always a good node.
Node 4 -> (3,4) is the maximum value in the path starting from the root.
Node 5 -> (3,4,5) is the maximum value in the path
Node 3 -> (3,1,3) is the maximum value in the path.

Example 2:

Input: root = [3,3,null,4,2]
Output: 3
Explanation: Node 2 -> (3, 3, 2) is not good, because "3" is higher than it.

Example 3:

Input: root = [1]
Output: 1
Explanation: Root is considered as good.

Constraints:

• The number of nodes in the binary tree is in the range [1, 10^5].

• Each node's value is between [-10^4, 10^4].

class Solution {
    public int helper(TreeNode root, long max) {
        if (root == null)
            return 0;
        int ans = root.val >= max ? 1 : 0;
        ans += helper(root.left, Math.max(max, root.val));
        ans += helper(root.right, Math.max(max, root.val));
        return ans;
    }

    public int goodNodes(TreeNode root) {
        return helper(root, Long.MIN_VALUE);
    }
}