#中序遍历，寻找插值位置并交换
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def recoverTree(self, root: Optional[TreeNode]) -> None:
"""
Do not return anything, modify root in-place instead.
"""
#记录中序遍历的值
nums = []
self.inorder(root, nums)
print(nums)
x,y = self.swappos(nums)
self.swap(root,2,x,y)
#找到替换值的位置
def inorder(self, root, nums):
if root:
self.inorder(root.left,nums)
nums.append(root.val)
self.inorder(root.right,nums)
def swappos(self, nums):
n = len(nums)
index1 = -1
index2 = -1
for i in range(n-1):
if nums[i+1] < nums[i]:
index1 = i+1
if index2 == -1:
index2 = i
else:
break
x,y = nums[index2], nums[index1]
return [x,y]
def swap(self, root, count, num1, num2):
if root:
if root.val == num1 or root.val == num2:
root.val = num2 if root.val == num1 else num1
count -= 1
if count == 0:
return
self.swap(root.left, count, num1, num2)
self.swap(root.right, count, num1, num2)#边中序遍历，边判断
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def recoverTree(self, root):
stack = []
x, y = None, None
prev = None
#迭代形式的中序遍历：借助栈
while stack or root:
#遍历左子树
while root:
stack.append(root)
root = root.left
#左子树遍历完，root为null
root = stack.pop()
if prev and root.val < prev.val:
x = root
if y == None:
y = prev
else:
break
#这个root判断完，将其赋予prev
prev = root
root = root.right
self.swap(x,y)
def swap(self,x,y):
tmp = y.val
y.val = x.val
x.val = tmp
#moriss遍历
class Solution:
def recoverTree(self, root):
x, y, pred, predecessor = None, None, None, None
while root:
if root.left:
predecessor = root.left
while predecessor.right and predecessor.right != root:
predecessor = predecessor.right
if predecessor.right == None:
predecessor.right = root
root = root.left
else:
predecessor.right = None
root = root.right
else:
root = root.right
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def recoverTree(self, root):
x, y, pred, predecessor = None, None, None, None
while root:
if root.left:
predecessor = root.left
while predecessor.right and predecessor.right != root:
predecessor = predecessor.right
if predecessor.right == None:
predecessor.right = root
root = root.left
else:
if pred and root.val < pred.val:
#y为后面那个值
y = root
if not x:
x = pred
pred = root
predecessor.right = None
root = root.right
else:
if pred and root.val < pred.val:
y = root
if not x:
x = pred
pred = root
root = root.right
x.val,y.val = y.val,x.val
