【leetcode】590. N-ary Tree Postorder Traversal

题目如下：

解题思路：凑数题+2，做完先序做后序。凑数博+2。

代码如下：

class Solution(object):
    def postorder(self, root):
        """
        :type root: Node
        :rtype: List[int]
        """
        if root == None:
            return []
        res = []
        stack = [root]
        while len(stack) > 0:
            node = stack.pop(0)
            res.insert(0,node.val)
            for i in node.children:
                stack.insert(0, i)
        return res