589. N-ary Tree Preorder Traversal.py

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

class Solution:
    def preorder(self, root: 'Node') -> List[int]:
        if not root:
            return []
        
        result = [root.val]
        if root.children:
            for child in root.children:
                result += self.preorder(child)
        return result