Merge pull request #2742 from keon/fix/treenode-dedup-falsy-zero

Fix falsy-zero bug in BST validation, deduplicate TreeNode

Author: keon

algorithms/tree/bst_array_to_bst.py

@@ -3,12 +3,7 @@
 convert it to a height balanced BST.
 """
 
-
-class TreeNode:
-    def __init__(self, x):
-        self.val = x
-        self.left = None
-        self.right = None
+from algorithms.common.tree_node import TreeNode
 
 
 def array_to_bst(nums):

algorithms/tree/bst_serialize_deserialize.py

@@ -1,8 +1,4 @@
-class TreeNode:
-    def __init__(self, x):
-        self.val = x
-        self.left = None
-        self.right = None
+from algorithms.common.tree_node import TreeNode
 
 
 def serialize(root):

algorithms/tree/bst_validate_bst.py

@@ -12,14 +12,7 @@
 """
 # ===============================================================================
 
-
-# Tree class definition
-class TreeNode:
-    def __init__(self, value):
-
-        self.val = value
-        self.left = None
-        self.right = None
+from algorithms.common.tree_node import TreeNode
 
 
 # Function to validate if a binary tree is a BST
@@ -46,24 +39,24 @@ def validate_bst(node):
     if not valid_left or not valid_right:
         return (
             False,
-            minn_left if minn_left else node.val,
-            maxx_right if maxx_right else node.val,
+            minn_left if minn_left is not None else node.val,
+            maxx_right if maxx_right is not None else node.val,
         )
 
     # Check the current node's value against the max of the left subtree
     if maxx_left is not None and maxx_left > node.val:
         return (
             False,
-            minn_left if minn_left else node.val,
-            maxx_right if maxx_right else node.val,
+            minn_left if minn_left is not None else node.val,
+            maxx_right if maxx_right is not None else node.val,
         )
 
     # Check the current node's value against the min of the right subtree
     if minn_right is not None and minn_right < node.val:
         return (
             False,
-            minn_left if minn_left else node.val,
-            maxx_right if maxx_right else node.val,
+            minn_left if minn_left is not None else node.val,
+            maxx_right if maxx_right is not None else node.val,
         )
 
     # If all checks pass, the tree/subtree is a valid BST

algorithms/tree/construct_tree_postorder_preorder.py

@@ -14,23 +14,7 @@
 
 from __future__ import annotations
 
-
-class TreeNode:
-    """A node in a binary tree.
-
-    Args:
-        val: The value stored in this node.
-        left: The left child node.
-        right: The right child node.
-    """
-
-    def __init__(
-        self, val: int, left: TreeNode | None = None, right: TreeNode | None = None
-    ) -> None:
-        self.val = val
-        self.left = left
-        self.right = right
-
+from algorithms.common.tree_node import TreeNode
 
 pre_index = 0