2025-07-30 15:44:00 +0000 UTC

N-ary Tree Preorder Traversal
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"""
# Definition for a Node.
class Node:
    def __init__(self, val: Optional[int] = None, children: Optional[List['Node']] = None):
        self.val = val
        self.children = children
"""

class Solution:
    def preorder(self, root: 'Node') -> List[int]:
        if root is None:
            return []
        res = []
        queue = deque((root, ))
        while queue:
            node = queue.popleft()
            res.append(node.val)
            queue.extendleft(reversed(node.children))
        return res