# 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
        return [self.front(root),self.middle(root),self.back(root)]

    def front(self,root,var=None):
        if root == None:
            return
        if var == None:
            var = []
        var.append(root.val)
        lt = self.front(root.left,var)
        rt = self.front(root.right,var)
        return var

    def middle(self,root,var=None):
        if root == None:
            return
        if var == None:
            var = []
        lt = self.middle(root.left,var)
        var.append(root.val)
        rt = self.middle(root.right,var)
        return var

    def back(self,root,var=None):
        if root == None:
            return
        if var == None:
            var = []
        lt = self.back(root.left,var)
        rt = self.back(root.right,var)
        var.append(root.val)
        return var