Most asked Binary Tree problem

Welcome back!

This week, we’ll cover the most popular Binary Tree problem. Are you ready for it?

Today we will cover:

• Invert Binary Tree

• How text search works

Read time: under 4 minutes

CODING CHALLENGE

Invert Binary Tree

Given the root of a binary tree, invert the tree, and return its root.

Example 1:

Input: root = [4,2,7,1,3,6,9]
Output: [4,7,2,9,6,3,1]

Solve the problem here before reading the solution.

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SOLUTION

To invert a binary tree, we need to swap the left and right children of every node in the tree. We can use a recursive approach to solve this problem.

For each node, we'll first recursively invert its left and right subtrees. Then, we'll swap its left and right children. The base case is when we reach a null node.

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

SYSTEM DESIGN

How text search works?

When you have a large database table with millions of records, searching through it can be painfully slow. Think about a table with customer information containing names, addresses, phone numbers, and other details.

Let’s say you want to find all customers whose name contains "Smith". Without a search index, the database has to check every single row in the table one by one. This is called a full table scan, and it's highly inefficient.

A search index solves this performance problem. It's a specialized data structure that stores your data in a way that makes searching much faster. When you search for "Smith" in a database with a proper search index, instead of checking every row, the database uses the index to jump directly to the relevant records.

This is possible because database contains a mapping between a word or token and the records that contain that token. This is similar to how any database index works. But search indexes are specifically designed to handle text searches efficiently. They can quickly find partial matches, handle different word forms, and even account for common misspellings.

Apache Lucene is one of the most popular open-source search index implementations. Lucene handles all the complex work of creating and maintaining search indexes like including breaking text into searchable terms, removing common words, and storing the processed data efficiently.

Elasticsearch, built on top of Lucene, takes these capabilities even further. It's a distributed search engine that can handle massive amounts of data across multiple servers. Many major websites and applications use Elasticsearch to power their search features. It provides a simple way to set up search functionality that can scale as your data grows, and it includes features like real-time search, automatic suggestions, and analytics capabilities.

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NEWS

This Week in the Tech World

Meta's Performance Cuts: Meta plans to cut 5% of its workforce, targeting low performers. CEO Zuckerberg aims to "raise the bar" on performance management. The company, with 72,000 employees, will notify affected staff by February 10, focusing on AI investments.

Microsoft Gaming Layoffs: Microsoft starts 2025 with new layoffs across sales, security, and gaming teams. Microsoft said the cuts were performance based and relatively "small".

ChatGPT Tasks Launch: OpenAI introduces Tasks feature for ChatGPT, allowing users to schedule future actions and reminders. Available to Plus, Team, and Pro subscribers, it aims to compete with traditional digital assistants. Limited to 10 active tasks.

TikTok Shutdown Looms: TikTok plans to cease US operations by January 19 due to federal ban unless ByteDance divests. The app, used by 170M Americans, faces shutdown as Supreme Court weighs the law's constitutionality. Users will get data download options.

US Tightens Chip Rules: Commerce Department strengthens restrictions on advanced computing semiconductors to prevent diversion to China. New rules expand licensing requirements for chip factories and packaging companies exporting certain advanced chips.

TikTok Users Switch to Xiaohongshu: As TikTok ban approaches, US users flock to Chinese app Xiaohongshu in protest, making it the top downloaded app. Self-described "TikTok refugees" embrace the platform despite censorship concerns.

BONUS

Just for laughs 😏

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