maximum-depth-of-n-ary-tree.py

"""
# Definition for a Node.
class Node:
    def __init__(self, val, children):
        self.val = val
        self.children = children
"""
class Solution(object):
    def maxDepth(self, root):
        if not root: return 0
        if not root.children: return 1
        return max(self.maxDepth(node) for node in root.children) + 1