add python 94 and python 1008

python-leetcode/README.md

@@ -49,6 +49,8 @@
 35. [二叉树剪枝](./solution/tree/leetcode_814_.py)
 36. [二叉搜索树中的插入操作](./solution/tree/leetcode_701_.py)
 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)
 
 
 

python-leetcode/solution/tree/leetcode_1008_.py

+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# coding=utf-8
+"""
+1008. 先序遍历构造二叉树
+"""
+from typing import List
+
+from solution import TreeNode
+
+
+class Solution:
+    def bstFromPreorder(self, preorder: List[int]) -> TreeNode:
+        def helper(root: TreeNode, val: int) -> TreeNode:
+            if not root:
+                return TreeNode(val)
+
+            if val > root.val:
+                root.right = helper(root.right, val)
+            else:
+                root.left = helper(root.left, val)
+            return root
+
+        root = TreeNode(preorder[0])
+        for v in preorder[1:]:
+            helper(root, v)
+        return root

python-leetcode/solution/tree/leetcode_94_.py

+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# coding=utf-8
+"""
+94. 二叉树的中序遍历
+"""
+from solution import TreeNode
+
+
+class Solution:
+    def inorderTraversal(self, root: TreeNode) -> List[int]:
+        stack = []
+        list = []
+        while root or len(stack) > 0:
+            while root:
+                stack.append(root)
+                root = root.left
+
+            node = stack.pop()
+            list.append(node.val)
+            root = node.right
+
+        return list