From b825b5a7c82023ee2ac1b2adc68cf75abc2ecd13 Mon Sep 17 00:00:00 2001
From: ZerenZhang2022 <118794589+ZerenZhang2022@users.noreply.github.com>
Date: Tue, 27 Dec 2022 00:30:43 -0500
Subject: [PATCH] =?UTF-8?q?Update=200098.=E9=AA=8C=E8=AF=81=E4=BA=8C?=
 =?UTF-8?q?=E5=8F=89=E6=90=9C=E7=B4=A2=E6=A0=91.md?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

补充：**递归** - 避免初始化最小值做法
---
 problems/0098.验证二叉搜索树.md | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/problems/0098.验证二叉搜索树.md b/problems/0098.验证二叉搜索树.md
index 95ae783f..93c2272c 100644
--- a/problems/0098.验证二叉搜索树.md
+++ b/problems/0098.验证二叉搜索树.md
@@ -392,7 +392,26 @@ class Solution:
             return is_left_valid and is_right_valid
         return __isValidBST(root)
 ```
-
+**递归** - 避免初始化最小值做法：
+```python
+class Solution:
+    def isValidBST(self, root: TreeNode) -> bool:
+        # 规律: BST的中序遍历节点数值是从小到大. 
+        pre = None
+        def __isValidBST(root: TreeNode) -> bool: 
+            nonlocal pre
+            
+            if not root: 
+                return True
+            
+            is_left_valid = __isValidBST(root.left)
+            if pre and pre.val>=root.val: return False
+            pre = root
+            is_right_valid = __isValidBST(root.right)
+            
+            return is_left_valid and is_right_valid
+        return __isValidBST(root)
+```
 ```python
 迭代-中序遍历
 class Solution: