python3题解 | #实现二叉树先序，中序和后序遍历#

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param root TreeNode类 the root of binary tree
# @return int整型二维数组
#
class Solution:
    def threeOrders(self , root: TreeNode) -> List[List[int]]:
        # write code here
        g1 = []
        g2 = []
        g3 = []
        def xian(root):
            if root:
                g1.append(root.val)
                xian(root.left)
                xian(root.right)
        def mid(root):
            if root:
                mid(root.left)
                g2.append(root.val)
                mid(root.right)
        def hou(root):
            if root:
                hou(root.left)
                hou(root.right)
                g3.append(root.val)
        xian(root)
        mid(root)
        hou(root)

        return [g1,g2,g3]