微信图片_20191219215206.jpg
class Solution:
def __init__(self):
self.firstNode = None
self.secondNode = None
self.preNode = TreeNode(float('-inf'))
def recoverTree(self, root: TreeNode) -> None:
"""
Do not return anything, modify root in-place instead.
"""
def order(root):
if not root:
return
order(root.left)
if self.firstNode == None and self.preNode.val >= root.val:
self.firstNode = self.preNode
if self.firstNode and self.preNode.val >= root.val:
self.secondNode = root
self.preNode = root
order(root.right)
order(root)
if self.firstNode and self.secondNode:
self.firstNode.val, self.secondNode.val = self.secondNode.val, self.firstNode.val
