Merge pull request #1248 from ChubbyPan/master

更新了文件<ACM模式如何构建二叉树>python3版本

problems/前序/ACM模式如何构建二叉树.md

@@ -266,7 +266,61 @@ public class Solution {
 
 ## Python 
 
-```Python
+```Python3
+class TreeNode:
+    def __init__(self, val = 0, left = None, right = None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+
+# 根据数组构建二叉树
+
+def construct_binary_tree(nums: []) -> TreeNode:
+    if not nums: 
+        return None
+    # 用于存放构建好的节点
+    root = TreeNode(-1)
+    Tree = []
+    # 将数组元素全部转化为树节点
+    for i in range(len(nums)):
+        if nums[i]!= -1:
+            node = TreeNode(nums[i])
+        else:
+            node = None
+        Tree.append(node)
+        if i == 0:
+            root = node
+    for i in range(len(Tree)):
+        node = Tree[i]
+        if node and (2 * i + 2) < len(Tree):
+            node.left = Tree[i * 2 + 1]
+            node.right = Tree[i * 2 + 2]
+    return root
+
+
+
+# 算法:中序遍历二叉树
+
+class Solution:
+    def __init__(self):
+        self.T = []
+    def inorder(self, root: TreeNode) -> []:
+        if not root:
+            return 
+        self.inorder(root.left)
+        self.T.append(root.val)
+        self.inorder(root.right)
+        return self.T
+
+
+
+# 验证创建二叉树的有效性,二叉排序树的中序遍历应为顺序排列
+
+test_tree = [3, 1, 5, -1, 2, 4 ,6]
+root = construct_binary_tree(test_tree)
+A = Solution()
+print(A.inorder(root))
 ```