Đếm các nút tốt trong cây nhị phân

def good_nodes_opt(root):
    if isinstance(root, list):
        r = build_tree(root)
        return good_nodes_opt_helper(r)
    return good_nodes_opt_helper(root)

def good_nodes_opt_helper(root: TreeNode) -> int:
    def dfs(node, max_val):
        if not node:
            return 0
        res = 1 if node.val >= max_val else 0
        max_val = max(max_val, node.val)
        res += dfs(node.left, max_val)
        res += dfs(node.right, max_val)
        return res
    return dfs(root, float('-inf'))

def good_nodes_brute(root):
    if isinstance(root, list):
        r = build_tree(root)
        return good_nodes_brute_helper(r)
    return good_nodes_brute_helper(root)

def good_nodes_brute_helper(root: TreeNode) -> int:
    def dfs(node, path):
        if not node: return 0
        is_good = 1 if all(x <= node.val for x in path) else 0
        path.append(node.val)
        left = dfs(node.left, path)
        right = dfs(node.right, path)
        path.pop()
        return is_good + left + right
    return dfs(root, [])