Max Consecutive Ones — Python

# Time:  O(n)
# Space: O(h)

class Node(object):
    def __init__(self, val, children):
        self.val = val
        self.children = children


class Solution(object):
    def maxDepth(self, root):
        """
        :type root: Node
        :rtype: int
        """
        if not root:
            return 0
        depth = 0
        for child in root.children:
            depth = max(depth, self.maxDepth(child))
        return 1+depth