算法刷题笔记05：Tree

class Solution(object):
    def preorderTraversal(self, root):
        """
        :type root: TreeNode
        :rtype: List[int]
        """
        return [root.val] + self.preorderTraversal(root.left) + self.preorderTraversal(root.right) if root else []

class Solution(object):
    def preorderTraversal(self, root):
        """
        :type root: TreeNode
        :rtype: List[int]
        """
        return self.preorderTraversal(root.left) + [root.val] + self.preorderTraversal(root.right) if root else []

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

class Solution(object):
    def preorder(self, root):
        """
        :type root: Node
        :rtype: List[int]
        """
        if root == None:return []
        res = [root.val]
        for node in root.children:
            res.extend(self.preorder(node))
        return res

class Solution(object):
    def postorder(self, root):
        """
        :type root: Node
        :rtype: List[int]
        """
        if root == None:return []
        res = []
        for node in root.children:
            res.extend(self.postorder(node))
        res.append(root.val)
        return res