590. N叉樹的後序遍歷

Difficulty: 簡單

給定一個 N 叉樹，返回其節點值的_後序遍歷_。

例如，給定一個3叉樹:

返回其後序遍歷: [5,6,3,2,4,1].

說明:遞迴法很簡單，你可以使用迭代法完成此題嗎?

Solution

Language: ****

"""
# Definition for a Node.
class Node:
   def __init__(self, val=None, children=None):
     self.val = val
     self.children = children
"""
​
class Solution:
  def postorder(self, root: 'Node') -> List[int]:
    res = []
    if not root: return res
​
    stack = [root]
    while stack:
      node = stack.pop()
      res.append(node.val)
      for i in node.children:
        stack.append(i)
    return res[::-1]