From 85e4c414571db69f8dd4c27c67928632845e65e4 Mon Sep 17 00:00:00 2001
From: jianghongcheng <35664721+jianghongcheng@users.noreply.github.com>
Date: Tue, 23 May 2023 20:56:07 -0500
Subject: [PATCH] =?UTF-8?q?Update=200530.=E4=BA=8C=E5=8F=89=E6=90=9C?=
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---
 .../0530.二叉搜索树的最小绝对差.md | 100 ++++++++++--------
 1 file changed, 58 insertions(+), 42 deletions(-)

diff --git a/problems/0530.二叉搜索树的最小绝对差.md b/problems/0530.二叉搜索树的最小绝对差.md
index fa1430de..3fe57702 100644
--- a/problems/0530.二叉搜索树的最小绝对差.md
+++ b/problems/0530.二叉搜索树的最小绝对差.md
@@ -204,66 +204,82 @@ class Solution {
 ```
 ## Python 
 
-递归
+递归法（版本一）利用中序递增，结合数组
 ```python
 class Solution:
-    def getMinimumDifference(self, root: TreeNode) -> int:
-        res = []   
-        r = float("inf")
-        def buildaList(root):  //把二叉搜索树转换成有序数组
-            if not root: return None
-            if root.left: buildaList(root.left)  //左
-            res.append(root.val)  //中
-            if root.right: buildaList(root.right)  //右
-            return res
-            
-        buildaList(root)
-        for i in range(len(res)-1):  // 统计有序数组的最小差值
-            r = min(abs(res[i]-res[i+1]),r)
-        return r
-        
-        
-class Solution: # 双指针法，不用数组 (同Carl写法) - 更快
-    def getMinimumDifference(self, root: Optional[TreeNode]) -> int:
-        global pre,minval
-        pre = None
-        minval = 10**5
-        self.traversal(root)
-        return minval
+    def __init__(self):
+        self.vec = []
 
-    def traversal(self,root):
-        global pre,minval
-        if not root: return None
+    def traversal(self, root):
+        if root is None:
+            return
         self.traversal(root.left)
-        if pre and root.val-pre.val<minval: 
-            minval = root.val-pre.val
-        pre = root
-        self.traversal(root.right)            
+        self.vec.append(root.val)  # 将二叉搜索树转换为有序数组
+        self.traversal(root.right)
+
+    def getMinimumDifference(self, root):
+        self.vec = []
+        self.traversal(root)
+        if len(self.vec) < 2:
+            return 0
+        result = float('inf')
+        for i in range(1, len(self.vec)):
+            # 统计有序数组的最小差值
+            result = min(result, self.vec[i] - self.vec[i - 1])
+        return result
+
 ```
 
 
-迭代法-中序遍历
+
+递归法（版本二）利用中序递增，找到该树最小值
 ```python 
 class Solution:
-    def getMinimumDifference(self, root: TreeNode) -> int:
+    def __init__(self):
+        self.result = float('inf')
+        self.pre = None
+
+    def traversal(self, cur):
+        if cur is None:
+            return
+        self.traversal(cur.left)  # 左
+        if self.pre is not None:  # 中
+            self.result = min(self.result, cur.val - self.pre.val)
+        self.pre = cur  # 记录前一个
+        self.traversal(cur.right)  # 右
+
+    def getMinimumDifference(self, root):
+        self.traversal(root)
+        return self.result
+
+        
+```
+
+迭代法
+```python 
+class Solution:
+    def getMinimumDifference(self, root):
         stack = []
         cur = root
         pre = None
         result = float('inf')
-        while cur or stack:
-            if cur: # 指针来访问节点，访问到最底层
-                stack.append(cur)
-                cur = cur.left
-            else: # 逐一处理节点
+
+        while cur is not None or len(stack) > 0:
+            if cur is not None:
+                stack.append(cur)  # 将访问的节点放进栈
+                cur = cur.left  # 左
+            else:
                 cur = stack.pop()
-                if pre: # 当前节点和前节点的值的差值
-                    result = min(result, abs(cur.val - pre.val))
+                if pre is not None:  # 中
+                    result = min(result, cur.val - pre.val)
                 pre = cur
-                cur = cur.right
+                cur = cur.right  # 右
+
         return result
+
+
         
 ```
-
 ## Go： 
 
 中序遍历，然后计算最小差值