fix failure

Author: lilyhe123

src/008.py

@@ -28,7 +28,7 @@
 
 """
 
-from ds.classes import TreeNode
+from ds import TreeNode
 
 
 def getUnivalTreeNum(node: object) -> int:

src/020.py

@@ -35,7 +35,7 @@
    use next pointer to point to its previous.
 """
 
-from ds.classes import LinkedNode
+from ds import LinkedNode
 
 
 def revert(head):

src/052.py

@@ -22,7 +22,7 @@
        if size > N, remove tail element
 """
 
-from ds.classes import DoubleLinkedList
+from ds import DoubleLinkedList
 
 
 class LRUCache:

src/067.py

@@ -50,7 +50,7 @@
 
 """
 
-from ds.classes import DoubleLinkedList, DoubleLinkedNode
+from ds import DoubleLinkedList, DoubleLinkedNode
 
 
 # !! class inheritance

src/ds/__init__.py

@@ -0,0 +1,3 @@
+from .classes import DoubleLinkedList, DoubleLinkedNode, LinkedNode, TreeNode
+
+__all__ = ["LinkedNode", "DoubleLinkedList", "DoubleLinkedNode", "TreeNode"]

src/ds/classes.py

@@ -98,3 +98,20 @@ def print(self):
                 s += ", "
             node = node.next
         print(s)
+
+
+class TreeNode:
+    def __init__(self, val: int, left: object = None, right: object = None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+    def print(self):
+        print(self.val)
+
+    def print_inorder(self):
+        if self.left:
+            self.print_inorder(self.left)
+        self.print()
+        if self.right:
+            self.print_inorder(self.right)