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

#
# 
# @param root TreeNode类 the root of binary tree
# @return int整型二维数组
#
pre = []
mid = []
last = []
def visitOrder(root):
    if root is None: return
    pre.append(root.val)
    visitOrder(root.left)
    mid.append(root.val)
    visitOrder(root.right)
    last.append(root.val)

class Solution:


    def threeOrders(self , root ):
        # write code here
        visitOrder(root)
        return [pre,mid,last]