Merge branch 'youngyangyang04:master' into master

problems/二叉树的递归遍历.md

@@ -170,7 +170,53 @@ class Solution {
 ```
 
 Python：
+```python3
+# 前序遍历-递归-LC144_二叉树的前序遍历
+class Solution:
+    def preorderTraversal(self, root: TreeNode) -> List[int]:
+        # 保存结果
+        result = []
+        
+        def traversal(root: TreeNode):
+            if root == None:
+                return
+            result.append(root.val) # 前序
+            traversal(root.left)    # 左
+            traversal(root.right)   # 右
 
+        traversal(root)
+        return result
+
+# 中序遍历-递归-LC94_二叉树的中序遍历
+class Solution:
+    def inorderTraversal(self, root: TreeNode) -> List[int]:
+        result = []
+
+        def traversal(root: TreeNode):
+            if root == None:
+                return
+            traversal(root.left)    # 左
+            result.append(root.val) # 中序
+            traversal(root.right)   # 右
+
+        traversal(root)
+        return result
+
+# 后序遍历-递归-LC145_二叉树的后序遍历
+class Solution:
+    def postorderTraversal(self, root: TreeNode) -> List[int]:
+        result = []
+
+        def traversal(root: TreeNode):
+            if root == None:
+                return
+            traversal(root.left)    # 左
+            traversal(root.right)   # 右
+            result.append(root.val) # 后序
+
+        traversal(root)
+        return result
+```
 
 Go：