def insertIntoBST(self, root: TreeNode, val: int) -> TreeNode:
if not root: return TreeNode(val)
if val > root.val:
root.right = self.insertIntoBST(root.right, val)
else:
root.left = self.insertIntoBST(root.left, val)
return root
# 1. None -> True
# 2. False
# 3. travserd the until True or Flase
# ptr is ALL
if root is None:
return True
if root.val <= largerThan or root.val >= lessThan:
return False
return self.isValidBSTRec(root.left, min(
lessThan, root.val), largerThan) and self.isValidBSTRec(
root.right, lessThan, max(root.val, largerThan))
if __name__ == '__main__':
tree1 = TreeNode(2)
tree1.left = TreeNode(1)
tree1.right = TreeNode(3)
sol = Solution()
assert sol.isValidBST(tree1) == True
tree2 = TreeNode(5)
tree2.left = TreeNode(1)
tree2.right = TreeNode(4)
tree2.right.left = TreeNode(3)
tree2.right.right = TreeNode(6)
assert sol.isValidBST(tree2) == False
tree3 = TreeNode(1)
tree3.left = TreeNode(1)
assert sol.isValidBST(tree3) == False
# def inorderTraversalTest(root: TreeNode) -> List[int]:
# stack, res = [root], []
# # 中序是先左后中后右
# while stack:
# temp = stack.pop()
# if temp:
# if temp.left:
# stack.append(temp.left)
# res.append(temp.left.val)
# if temp.right:
# stack.append(temp.right)
# res.append(temp.val)
# return res
if __name__ == '__main__':
tree = TreeNode(6)
tree.left = TreeNode(8)
tree.right = TreeNode(4)
# tree.left.left = TreeNode(9)
# tree.left.right = TreeNode(7)
# tree.right.left = TreeNode(5)
# tree.right.right = TreeNode(3)
print(bfs(tree))
print("---------")
print(dfs(tree))
print('---------')
print(f'inorder is {inorderTraversal(tree)}')
print(f'dfs preorder is {dfsPreorder(tree)}')
print(f'dfs postorder is {dfsPostorder(tree)}')
# print(f'inorderTravsalTest is {inorderTraversalTest(tree)}')