/
0450.py
39 lines (37 loc) · 1.39 KB
/
0450.py
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# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def deleteNode(self, root: TreeNode, key: int) -> TreeNode:
# 树为空
if root == None:
return None
# 找到 key,进行删除
if root.val == key:
# 情况 1:两个子节点都为空
# 情况 2:只有一个非空子节点,让这个孩子取代自己
if root.left == None:
return root.right
if root.right == None:
return root.left
# 情况 3:有两个非空子节点,找到左子树的最大值,或者右子树的最小值,取代自己
# Python3 需要先有一个 TreeNode 对象
minNode = TreeNode(None)
minNode = self.getMin(root.right)
root.val = minNode.val
root.right = self.deleteNode(root.right, minNode.val)
# key 在左子树
elif root.val > key:
root.left = self.deleteNode(root.left, key)
# key 在右子树
elif root.val < key:
root.right = self.deleteNode(root.right, key)
return root
def getMin(self, node: TreeNode):
# BST 最左边的是最小值
while node.left != None:
node = node.left
return node