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What’s the difference between a Binary Tree and Binary Search Tree (BST)? Let’s understand this by solving the most asked BST problem.

Today we will cover:

• Validate Binary Search Tree

• ACID vs BASE Consistency

Read time: under 4 minutes

CODING CHALLENGE

Validate Binary Search Tree

Given the root of a binary tree, determine if it is a valid binary search tree (BST).

A valid BST is defined as follows:

• The left subtree of a node contains only nodes with keys less than the node's key.

• The right subtree of a node contains only nodes with keys greater than the node's key.

• Both the left and right subtrees must also be binary search trees.

Example 1:

Input: root = [2,1,3]
Output: true

Example 2:

Input: root = [5,1,4,null,null,3,6]
Output: false
Explanation: The root node's value is 5 but its right child's value is 4.

Solve the problem here before reading the solution.

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SOLUTION

To validate a Binary Search Tree, we can use a recursive approach. Each node must be within a valid range based on its position in the tree.

For the left subtree, the values must be less than the parent node's value, and for the right subtree, the values must be greater than the parent node's value.

We'll pass minimum and maximum allowed values for each node during recursion. If at any point a node's value falls outside its valid range, we return False. If we successfully traverse the entire tree, we return True.

The time complexity of this solution is O(n), where n is the number of nodes in the tree.

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SYSTEM DESIGN

ACID vs BASE Consistency

When building distributed systems, one of the key decisions is choosing between ACID and BASE consistency models. This choice can significantly impact how your system handles data and responds to failures.

ACID (Atomicity, Consistency, Isolation, Durability) is the traditional approach used by most relational databases. It ensures that data remains accurate and consistent at all times. If a transaction fails, all changes are rolled back, leaving the database in its original state. Think of a bank transfer - either both accounts are updated, or neither is.

BASE (Basically Available, Soft state, Eventually consistent) takes a different approach. Instead of guaranteeing immediate consistency, it prioritizes availability. Changes might take some time to propagate through the system, but eventually, all parts will have the same data. Think of social media likes - you might not see the exact count immediately, but it will become accurate over time.

ACID is better when accuracy is crucial, like in financial systems or inventory management. Bu it can be slower and less available during network issues because it needs all parts of the system to communicate to maintain consistency.

BASE works well for systems that can tolerate temporary inconsistencies, like social media or content delivery networks. It offers better performance and availability because operations can continue even when parts of the system are disconnected.

Here's a comparison of ACID and BASE:

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NEWS

This Week in the Tech World

Apple Reboots Siri With Gemini: Apple unveiled an overhauled Siri running on Google's Gemini, housed in a standalone app with visual intelligence and cross-app awareness. Software updates span iOS 27 to macOS 27, though Siri AI skips Europe and China over regulatory hurdles.

DeepSeek Lands First Outside Funding: China's DeepSeek is set to raise roughly $7.4 billion in its debut round, valuing it between $52 billion and $59 billion. Tencent and battery giant CATL anchor the deal, with founder Liang Wenfeng committing $2.8 billion of his own.

Supabase Hits $10.5 Billion: Riding the vibe-coding wave, open-source database startup Supabase raised $500 million in a GIC-led round that values it at $10.5 billion. The platform has become a favorite among developers building AI apps.

Bezos Backs Brain-Inspired AI: Flourish, a New York startup building AI models modeled on the human brain, raised $500 million in initial funding. Backers include Jeff Bezos, Lux Capital, and Google Ventures.

Amdocs Cuts Thousands Of Jobs: Telecom software giant Amdocs is preparing to lay off close to 2,900 workers, including hundreds in Israel, under new CEO Shimie Hortig. The reorganization aims to flatten the company and reshape it for the AI era.

French Telecoms Carve Up SFR: A consortium of French operators agreed to buy Patrick Drahi's debt-laden carrier SFR for about $23.5 billion, breaking up one of France's largest mobile and broadband players among its rivals.

Publishers Hit Google With Claim: More than 20 European news publishers filed a damages claim against Google in the Netherlands, seeking over €640 million tied to its dominance in the adtech market.

Suno Strikes A $5.4 Billion Chord: AI music startup Suno raised $400 million in Series D funding, lifting its valuation to $5.4 billion as labels and artists keep sparring with generative music tools.

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