add python 1325 and python 230

python-leetcode/README.md

@@ -51,6 +51,8 @@
 37. [二叉搜索树迭代器](./solution/tree/leetcode_173_.py)
 38. [二叉树的中序遍历](./solution/tree/leetcode_94_.py)
 39. [先序遍历构造二叉树](./solution/tree/leetcode_1008_.py)
+40. [二叉搜索树中第K小的元素](./solution/tree/leetcode_230_.py)
+41. [删除给定值的叶子节点](./solution/tree/leetcode_1325_.py)
 
 
 

python-leetcode/solution/tree/leetcode_1325_.py

+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# coding=utf-8
+"""
+1325. 删除给定值的叶子节点
+"""
+from solution import TreeNode
+
+
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution:
+    def removeLeafNodes(self, root: TreeNode, target: int) -> TreeNode:
+        if not root:
+            return None
+
+        root.left = self.removeLeafNodes(root.left, target)
+        root.right = self.removeLeafNodes(root.right, target)
+        if not root.left and not root.right and root.val == target:
+            return None
+        else:
+            return root

python-leetcode/solution/tree/leetcode_230_.py

+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# coding=utf-8
+"""
+230. 二叉搜索树中第K小的元素
+"""
+from solution import TreeNode
+
+
+class Solution:
+    def kthSmallest(self, root: TreeNode, k: int) -> int:
+        count = 0
+        min = 0
+
+        def helper(root: TreeNode, k: int):
+            nonlocal count, min
+            if root:
+                helper(root.left, k)
+                count += 1
+                if count == k:
+                    min = root.val
+                helper(root.right, k)
+
+        helper(root, k)
+        return min