559. Maximum Depth of N-ary Tree

Given a n-ary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples).

 

Example 1:

Input: root = [1,null,3,2,4,null,5,6]
Output: 3

Example 2:

Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
Output: 5

 

Constraints:

• The total number of nodes is in the range [0, 104].
• The depth of the n-ary tree is less than or equal to 1000.

---

"""
# Definition for a Node.
class Node:
    def __init__(self, val=None, children=None):
        self.val = val
        self.children = children
"""

class Solution:
    def maxDepth(self, root: 'Node') -> int:
        self.ans=1
        if not root:
            return 0
        
        def dfs(node, depth):
            self.ans=max(self.ans, depth)
            
            for c in node.children:
                dfs(c, depth+1)
            
        dfs(root,1)
        return self.ans