May 27, 2023 · Dec 7, 2022 · Dec 9, 2022 · Mar 19, 2023 · Mar 20, 2023 · Mar 20, 2023
diff --git a/problems/0669.修剪二叉搜索树.md b/problems/0669.修剪二叉搜索树.md
Original file line number	Diff line number	Diff line change
Expand Up		@@ -271,64 +271,72 @@ class Solution {

		## Python

	递归

	递归法(版本一)
		```python
	# 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 trimBST(self, root: TreeNode, low: int, high: int) -> TreeNode:
	'''
	确认递归函数参数以及返回值:返回更新后剪枝后的当前root节点
	'''
	# Base Case
	if not root: return None

	# 单层递归逻辑
	if root is None:
	return None
		if root.val < low:
	# 若当前root节点小于左界:只考虑其右子树,用于替代更新后的其本身,抛弃其左子树整体
	# 寻找符合区间 [low, high] 的节点
		return self.trimBST(root.right, low, high)

	if high < root.val:
	# 若当前root节点大于右界:只考虑其左子树,用于替代更新后的其本身,抛弃其右子树整体
	if root.val > high:
	# 寻找符合区间 [low, high] 的节点
		return self.trimBST(root.left, low, high)
	root.left = self.trimBST(root.left, low, high) # root.left 接入符合条件的左孩子
	root.right = self.trimBST(root.right, low, high) # root.right 接入符合条件的右孩子
	return root

	if low <= root.val <= high:
	root.left = self.trimBST(root.left, low, high)
	root.right = self.trimBST(root.right, low, high)
	# 返回更新后的剪枝过的当前节点root
	return root
		```
	递归法(版本二)精简
	```python
	class Solution:
	def trimBST(self, root: TreeNode, low: int, high: int) -> TreeNode:
	if root is None:
	return None
	if root.val < low:
	return self.trimBST(root.right, low, high)
	if root.val > high:
	return self.trimBST(root.left, low, high)
	root.left = self.trimBST(root.left, low, high)
	root.right = self.trimBST(root.right, low, high)
	return root

	迭代

	```

	迭代法
		```python
		class Solution:
	def trimBST(self, root: Optional[TreeNode], low: int, high: int) -> Optional[TreeNode]:
	if not root: return root
	# 处理头结点,让root移动到[L, R] 范围内,注意是左闭右开
	while root and (root.val < low or root.val > high):
	if root.val < low: # 小于L往右走
	root = root.right
	else: # 大于R往左走
	root = root.left
	# 此时root已经在[L, R] 范围内,处理左孩子元素小于L的情况
	def trimBST(self, root: TreeNode, L: int, R: int) -> TreeNode:
	if not root:
	return None

	# 处理头结点,让root移动到[L, R] 范围内,注意是左闭右闭
	while root and (root.val < L or root.val > R):
	if root.val < L:
	root = root.right # 小于L往右走
	else:
	root = root.left # 大于R往左走

		cur = root

	# 此时root已经在[L, R] 范围内,处理左孩子元素小于L的情况
		while cur:
	while cur.left and cur.left.val < low:
	while cur.left and cur.left.val < L:
		cur.left = cur.left.right
		cur = cur.left
	# 此时root已经在[L, R] 范围内,处理右孩子大于R的情况

		cur = root

	# 此时root已经在[L, R] 范围内,处理右孩子大于R的情况
		while cur:
	while cur.right and cur.right.val > high:
	while cur.right and cur.right.val > R:
		cur.right = cur.right.left
		cur = cur.right

		return root

		```

		## Go
Expand Down