题解 | #实现二叉树先序，中序和后序遍历#
实现二叉树先序，中序和后序遍历
https://www.nowcoder.com/practice/a9fec6c46a684ad5a3abd4e365a9d362
# 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 __init__(self):
self.ls_pre=[]
self.ls_in=[]
self.ls_post=[]
def pre_order(self,node):
if node:
self.ls_pre.append(node.val)
self.pre_order(node.left)
self.pre_order(node.right)
def in_order(self,node):
if node:
self.in_order(node.left)
self.ls_in.append(node.val)
self.in_order(node.right)
def post_order(self,node):
if node:
self.post_order(node.left)
self.post_order(node.right)
self.ls_post.append(node.val)
def threeOrders(self , root: TreeNode) -> List[List[int]]:
res=[]
self.pre_order(root)
res.append(self.ls_pre)
self.in_order(root)
res.append(self.ls_in)
self.post_order(root)
res.append(self.ls_post)
return res
