Update 0235.二叉搜索树的最近公共祖先.md

problems/0235.二叉搜索树的最近公共祖先.md

@@ -275,34 +275,57 @@ class Solution {
 
 ## Python
 
-递归法：
+递归法（版本一）
 ```python
 class Solution:
-    """二叉搜索树的最近公共祖先 递归法"""
+    def traversal(self, cur, p, q):
+        if cur is None:
+            return cur
+                                                        # 中
+        if cur.val > p.val and cur.val > q.val:           # 左
+            left = self.traversal(cur.left, p, q)
+            if left is not None:
+                return left
 
-    def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
+        if cur.val < p.val and cur.val < q.val:           # 右
-        if root.val > p.val and root.val > q.val:
+            right = self.traversal(cur.right, p, q)
-            return self.lowestCommonAncestor(root.left, p, q)
+            if right is not None:
-        if root.val < p.val and root.val < q.val:
+                return right
-            return self.lowestCommonAncestor(root.right, p, q)
+
-        return root
+        return cur
+
+    def lowestCommonAncestor(self, root, p, q):
+        return self.traversal(root, p, q)
 ```
 
-迭代法：
+迭代法（版本二）精简
 ```python
 class Solution:
-    """二叉搜索树的最近公共祖先 迭代法"""
+    def lowestCommonAncestor(self, root, p, q):
+        if root.val > p.val and root.val > q.val:
+            return self.lowestCommonAncestor(root.left, p, q)
+        elif root.val < p.val and root.val < q.val:
+            return self.lowestCommonAncestor(root.right, p, q)
+        else:
+            return root
 
-    def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
+```
-        while True:
+
+迭代法
+```python
+class Solution:
+    def lowestCommonAncestor(self, root, p, q):
+        while root:
             if root.val > p.val and root.val > q.val:
                 root = root.left
             elif root.val < p.val and root.val < q.val:
                 root = root.right
             else:
                 return root
-```
+        return None
 
+
+```
 ## Go 
 
 递归法：