From 14acf5a55469e766e05b74f2279132ce2a7b66d7 Mon Sep 17 00:00:00 2001
From: jianghongcheng <35664721+jianghongcheng@users.noreply.github.com>
Date: Tue, 23 May 2023 21:57:22 -0500
Subject: [PATCH] =?UTF-8?q?Update=200538.=E6=8A=8A=E4=BA=8C=E5=8F=89?=
 =?UTF-8?q?=E6=90=9C=E7=B4=A2=E6=A0=91=E8=BD=AC=E6=8D=A2=E4=B8=BA=E7=B4=AF?=
 =?UTF-8?q?=E5=8A=A0=E6=A0=91.md?=
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---
 ...38.把二叉搜索树转换为累加树.md | 53 +++++++++++++++++--
 1 file changed, 50 insertions(+), 3 deletions(-)

diff --git a/problems/0538.把二叉搜索树转换为累加树.md b/problems/0538.把二叉搜索树转换为累加树.md
index ad5310e1..ad4decc5 100644
--- a/problems/0538.把二叉搜索树转换为累加树.md
+++ b/problems/0538.把二叉搜索树转换为累加树.md
@@ -200,8 +200,30 @@ 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 convertBST(self, root: TreeNode) -> TreeNode:
+        self.pre = 0  # 记录前一个节点的数值
+        self.traversal(root)
+        return root
+    def traversal(self, cur):
+        if cur is None:
+            return        
+        self.traversal(cur.right)
+        cur.val += self.pre
+        self.pre = cur.val
+        self.traversal(cur.left)
+    
+        
+```
+递归法（版本二）
 ```python
 # Definition for a binary tree node.
 # class TreeNode:
@@ -234,7 +256,32 @@ class Solution:
         return root 
         
 ```
-**迭代**
+迭代法（版本一）
+```python
+class Solution:
+    def __init__(self):
+        self.pre = 0  # 记录前一个节点的数值
+    
+    def traversal(self, root):
+        stack = []
+        cur = root
+        while cur or stack:
+            if cur:
+                stack.append(cur)
+                cur = cur.right  # 右
+            else:
+                cur = stack.pop()  # 中
+                cur.val += self.pre
+                self.pre = cur.val
+                cur = cur.left  # 左
+    
+    def convertBST(self, root):
+        self.pre = 0
+        self.traversal(root)
+        return root
+
+```            
+迭代法（版本二）
 ```python
 class Solution:
     def convertBST(self, root: Optional[TreeNode]) -> Optional[TreeNode]: