# coding=utf-8

# author: Xiguang Liu<[email protected]>

# 2018-04-29 15:09

# 题目描述：https://www.nowcoder.com/practice/947f6eb80d944a84850b0538bf0ec3a5?tpId=13&tqId=11179&tPage=1&rp=1&ru=%2Fta%2Fcoding-interviews&qru=%2Fta%2Fcoding-interviews%2Fquestion-ranking

class TreeNode:

def __init__(self, x):

self.val = x

self.left = None

self.right = None

class Solution:

def __init__(self):

# 记录上一次访问的结点，上一次访问的结点为 None

self.pre = None

def Convert(self, pRootOfTree):

"""

BST的中序遍历顺序就是从小到大的排序

"""

self.inOrder(pRootOfTree)

# 寻找第一个结点作为返回值

if pRootOfTree:

while pRootOfTree.left:

pRootOfTree = pRootOfTree.left

return pRootOfTree

def inOrder(self, node):

if node is None:

return

self.inOrder(node.left)

node.left = self.pre

if self.pre:

self.pre.right = node

self.pre = node

self.inOrder(node.right)

import unittest

class TestCase(unittest.TestCase):

def setUp(self):

self.s = Solution()

def test_1(self):

root = TreeNode(8)

root.left = TreeNode(5)

root.right = TreeNode(10)

root.left.left = TreeNode(3)

root.left.right = TreeNode(6)

root.right.left = TreeNode(9)

root.right.right = TreeNode(11)

r = self.s.Convert(root)

print(r)