Coding Interview Resources
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This channel contains the free resources and solution of coding problems which are usually asked in the interviews.

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DSA (Data Structures and Algorithms) Essential Topics for Interviews

1️⃣ Arrays and Strings

Basic operations (insert, delete, update)

Two-pointer technique

Sliding window

Prefix sum

Kadane’s algorithm

Subarray problems


2️⃣ Linked List

Singly & Doubly Linked List

Reverse a linked list

Detect loop (Floyd’s Cycle)

Merge two sorted lists

Intersection of linked lists


3️⃣ Stack & Queue

Stack using array or linked list

Queue and Circular Queue

Monotonic Stack/Queue

LRU Cache (LinkedHashMap/Deque)

Infix to Postfix conversion


4️⃣ Hashing

HashMap, HashSet

Frequency counting

Two Sum problem

Group Anagrams

Longest Consecutive Sequence


5️⃣ Recursion & Backtracking

Base cases and recursive calls

Subsets, permutations

N-Queens problem

Sudoku solver

Word search


6️⃣ Trees & Binary Trees

Traversals (Inorder, Preorder, Postorder)

Height and Diameter

Balanced Binary Tree

Lowest Common Ancestor (LCA)

Serialize & Deserialize Tree


7️⃣ Binary Search Trees (BST)

Search, Insert, Delete

Validate BST

Kth smallest/largest element

Convert BST to DLL


8️⃣ Heaps & Priority Queues

Min Heap / Max Heap

Heapify

Top K elements

Merge K sorted lists

Median in a stream


9️⃣ Graphs

Representations (adjacency list/matrix)

DFS, BFS

Cycle detection (directed & undirected)

Topological Sort

Dijkstra’s & Bellman-Ford algorithm

Union-Find (Disjoint Set)


10️⃣ Dynamic Programming (DP)

0/1 Knapsack

Longest Common Subsequence

Matrix Chain Multiplication

DP on subsequences

Memoization vs Tabulation


11️⃣ Greedy Algorithms

Activity selection

Huffman coding

Fractional knapsack

Job scheduling


12️⃣ Tries

Insert and search a word

Word search

Auto-complete feature


13️⃣ Bit Manipulation

XOR, AND, OR basics

Check if power of 2

Single Number problem

Count set bits

Coding Interview Resources: https://whatsapp.com/channel/0029VammZijATRSlLxywEC3X

ENJOY LEARNING 👍👍
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Best Programming Languages for Hacking:

1. Python
It’s no surprise that Python tops our list. Referred to as the defacto hacking programing language, Python has indeed played a significant role in the writing of hacking scripts, exploits, and malicious programs.

2. C
C is critical language in the Hacking community. Most of the popular operating systems we have today run on a foundation of C language.
C is an excellent resource in reverse engineering of software and applications. These enable hackers to understand the working of a system or an app.

3. Javascript
For quite some time, Javascript(JS) was a client-side scripting language. With the release of Node.js, Javascript now supports backend development. To hackers, this means a broader field of exploitation.

4. PHP
For a long time now, PHP has dominated the backend of most websites and web applications.
If you are into web hacking, then getting your hands on PHP would be of great advantage.

5. C++
Have you ever thought of cracking corporate(paid) software? Here is your answer. The hacker community has significantly implemented C++ programming language to remove trial periods on paid software and even the operating system.

6. SQL
SQL – Standard Query Language. It is a programming language used to organize, add, retrieve, remove, or edit data in a database. A lot of systems store their data in databases such as MySQL, MS SQL, and PostgreSQL.
Using SQL, hackers can perform an attack known as SQL injection, which will enable them to access confidential information.

7. Java
Despite what many may say, a lot of backdoor exploits in systems are written in Java. It has also been used by hackers to perform identity thefts, create botnets, and even perform malicious activities on the client system undetected.
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10 Ways to Speed Up Your Python Code

1. List Comprehensions
numbers = [x**2 for x in range(100000) if x % 2 == 0]
instead of
numbers = []
for x in range(100000):
if x % 2 == 0:
numbers.append(x**2)

2. Use the Built-In Functions
Many of Python’s built-in functions are written in C, which makes them much faster than a pure python solution.

3. Function Calls Are Expensive
Function calls are expensive in Python. While it is often good practice to separate code into functions, there are times where you should be cautious about calling functions from inside of a loop. It is better to iterate inside a function than to iterate and call a function each iteration.

4. Lazy Module Importing
If you want to use the time.sleep() function in your code, you don't necessarily need to import the entire time package. Instead, you can just do from time import sleep and avoid the overhead of loading basically everything.

5. Take Advantage of Numpy
Numpy is a highly optimized library built with C. It is almost always faster to offload complex math to Numpy rather than relying on the Python interpreter.

6. Try Multiprocessing
Multiprocessing can bring large performance increases to a Python script, but it can be difficult to implement properly compared to other methods mentioned in this post.

7. Be Careful with Bulky Libraries
One of the advantages Python has over other programming languages is the rich selection of third-party libraries available to developers. But, what we may not always consider is the size of the library we are using as a dependency, which could actually decrease the performance of your Python code.

8. Avoid Global Variables
Python is slightly faster at retrieving local variables than global ones. It is simply best to avoid global variables when possible.

9. Try Multiple Solutions
Being able to solve a problem in multiple ways is nice. But, there is often a solution that is faster than the rest and sometimes it comes down to just using a different method or data structure.

10. Think About Your Data Structures
Searching a dictionary or set is insanely fast, but lists take time proportional to the length of the list. However, sets and dictionaries do not maintain order. If you care about the order of your data, you can’t make use of dictionaries or sets.
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Want To become a Backend Developer?

Here’s a roadmap with essential concepts:

1. Programming Languages

JavaScript (Node.js), Python, Java, Ruby, Go, or PHP: Pick one language and get comfortable with syntax & basics.


2. Version Control

Git: Learn version control basics, commit changes, branching, and collaboration on GitHub/GitLab.


3. Databases

Relational Databases: Master SQL basics with databases like MySQL or PostgreSQL. Learn how to design schemas, write efficient queries, and perform joins.
NoSQL Databases: Understand when to use NoSQL (MongoDB, Cassandra) vs. SQL. Learn data modeling for NoSQL.


4. APIs & Web Services

REST APIs: Learn how to create, test, and document RESTful services using tools like Postman.
GraphQL: Gain an understanding of querying and mutation, and when GraphQL may be preferred over REST.
gRPC: Explore gRPC for high-performance communication between services if your stack supports it.


5. Server & Application Frameworks

Frameworks: Master backend frameworks in your chosen language (e.g., Express for Node.js, Django for Python, Spring Boot for Java).
Routing & Middleware: Learn how to structure routes, manage requests, and use middleware.


6. Authentication & Authorization

JWT: Learn how to manage user sessions and secure APIs using JSON Web Tokens.
OAuth2: Understand OAuth2 for third-party authentication (e.g., Google, Facebook).
Session Management: Learn to implement secure session handling and token expiration.


7. Caching

Redis or Memcached: Learn caching to optimize performance, improve response times, and reduce load on databases.
Browser Caching: Set up HTTP caching headers for browser caching of static resources.


8. Message Queues & Event-Driven Architecture

Message Brokers: Learn message queues like RabbitMQ, Kafka, or AWS SQS for handling asynchronous processes.
Pub/Sub Pattern: Understand publish/subscribe patterns for decoupling services.


9. Microservices & Distributed Systems

Microservices Design: Understand service decomposition, inter-service communication, and Bounded Contexts.
Distributed Systems: Learn fundamentals like the CAP Theorem, data consistency models, and resiliency patterns (Circuit Breaker, Bulkheads).


10. Testing & Debugging

Unit Testing: Master unit testing for individual functions.
Integration Testing: Test interactions between different parts of the system.
End-to-End (E2E) Testing: Simulate real user scenarios to verify application behavior.
Debugging: Use logs, debuggers, and tracing to locate and fix issues.

11. Containerization & Orchestration

Docker: Learn how to containerize applications for easy deployment and scaling.
Kubernetes: Understand basics of container orchestration, scaling, and management.


12. CI/CD (Continuous Integration & Continuous Deployment)

CI/CD Tools: Familiarize yourself with tools like Jenkins, GitHub Actions, or GitLab CI/CD.
Automated Testing & Deployment: Automate tests, builds, and deployments for rapid development cycles.


13. Cloud Platforms

AWS, Azure, or Google Cloud: Learn basic cloud services such as EC2 (compute), S3 (storage), and RDS (databases).
Serverless Functions: Explore serverless options like AWS Lambda for on-demand compute resources.


14. Logging & Monitoring

Centralized Logging: Use tools like ELK Stack (Elasticsearch, Logstash, Kibana) for aggregating and analyzing logs.
Monitoring & Alerting: Implement real-time monitoring with Prometheus, Grafana, or CloudWatch.


15. Security

Data Encryption: Encrypt data at rest and in transit using SSL/TLS and other encryption standards.
Secure Coding: Protect against common vulnerabilities (SQL injection, XSS, CSRF).
Zero Trust Architecture: Learn to design systems with the principle of least privilege and regular authentication.


16. Scalability & Optimization

Load Balancing: Distribute traffic evenly across servers.
Database Optimization: Learn indexing, sharding, and partitioning.
Horizontal vs. Vertical Scaling: Know when to scale by adding resources to existing servers or by adding more servers.

ENJOY LEARNING 👍👍

#backend
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Tools & Tech Every Developer Should Know ⚒️👨🏻‍💻

❯ VS Code ➟ Lightweight, Powerful Code Editor
❯ Postman ➟ API Testing, Debugging
❯ Docker ➟ App Containerization
❯ Kubernetes ➟ Scaling & Orchestrating Containers
❯ Git ➟ Version Control, Team Collaboration
❯ GitHub/GitLab ➟ Hosting Code Repos, CI/CD
❯ Figma ➟ UI/UX Design, Prototyping
❯ Jira ➟ Agile Project Management
❯ Slack/Discord ➟ Team Communication
❯ Notion ➟ Docs, Notes, Knowledge Base
❯ Trello ➟ Task Management
❯ Zsh + Oh My Zsh ➟ Advanced Terminal Experience
❯ Linux Terminal ➟ DevOps, Shell Scripting
❯ Homebrew (macOS) ➟ Package Manager
❯ Anaconda ➟ Python & Data Science Environments
❯ Pandas ➟ Data Manipulation in Python
❯ NumPy ➟ Numerical Computation
❯ Jupyter Notebooks ➟ Interactive Python Coding
❯ Chrome DevTools ➟ Web Debugging
❯ Firebase ➟ Backend as a Service
❯ Heroku ➟ Easy App Deployment
❯ Netlify ➟ Deploy Frontend Sites
❯ Vercel ➟ Full-Stack Deployment for Next.js
❯ Nginx ➟ Web Server, Load Balancer
❯ MongoDB ➟ NoSQL Database
❯ PostgreSQL ➟ Advanced Relational Database
❯ Redis ➟ Caching & Fast Storage
❯ Elasticsearch ➟ Search & Analytics Engine
❯ Sentry ➟ Error Monitoring
❯ Jenkins ➟ Automate CI/CD Pipelines
❯ AWS/GCP/Azure ➟ Cloud Services & Deployment
❯ Swagger ➟ API Documentation
❯ SASS/SCSS ➟ CSS Preprocessors
❯ Tailwind CSS ➟ Utility-First CSS Framework

React ❤️ if you found this helpful

Coding Jobs: https://whatsapp.com/channel/0029VatL9a22kNFtPtLApJ2L
5
Top Libraries & Frameworks by Language 📚💻

❯ Python
 • Pandas ➟ Data Analysis
 • NumPy ➟ Math & Arrays
 • Scikit-learn ➟ Machine Learning
 • TensorFlow / PyTorch ➟ Deep Learning
 • Flask / Django ➟ Web Development
 • OpenCV ➟ Image Processing

❯ JavaScript / TypeScript
 • React ➟ UI Development
 • Vue ➟ Lightweight SPAs
 • Angular ➟ Enterprise Apps
 • Next.js ➟ Full-Stack Web
 • Express ➟ Backend APIs
 • Three.js ➟ 3D Web Graphics

❯ Java
 • Spring Boot ➟ Microservices
 • Hibernate ➟ ORM
 • Apache Maven ➟ Build Automation
 • Apache Kafka ➟ Real-Time Data

❯ C++
 • Boost ➟ Utility Libraries
 • Qt ➟ GUI Applications
 • Unreal Engine ➟ Game Development

❯ C#
 • .NET / ASP.NET ➟ Web Apps
 • Unity ➟ Game Development
 • Entity Framework ➟ ORM

❯ R
 • ggplot2 ➟ Data Visualization
 • dplyr ➟ Data Manipulation
 • caret ➟ Machine Learning
 • Shiny ➟ Interactive Dashboards

❯ PHP
 • Laravel ➟ Full-Stack Web
 • Symfony ➟ Web Framework
 • PHPUnit ➟ Testing

❯ Go (Golang)
 • Gin ➟ Web Framework
 • Gorilla ➟ Web Toolkit
 • GORM ➟ ORM for Go

❯ Rust
 • Actix ➟ Web Framework
 • Rocket ➟ Web Development
 • Tokio ➟ Async Runtime

Coding Resources: https://whatsapp.com/channel/0029VahiFZQ4o7qN54LTzB17

React with ❤️ for more useful content
4
DSA (Data Structures and Algorithms) Essential Topics for Interviews

1️⃣ Arrays and Strings

Basic operations (insert, delete, update)

Two-pointer technique

Sliding window

Prefix sum

Kadane’s algorithm

Subarray problems


2️⃣ Linked List

Singly & Doubly Linked List

Reverse a linked list

Detect loop (Floyd’s Cycle)

Merge two sorted lists

Intersection of linked lists


3️⃣ Stack & Queue

Stack using array or linked list

Queue and Circular Queue

Monotonic Stack/Queue

LRU Cache (LinkedHashMap/Deque)

Infix to Postfix conversion


4️⃣ Hashing

HashMap, HashSet

Frequency counting

Two Sum problem

Group Anagrams

Longest Consecutive Sequence


5️⃣ Recursion & Backtracking

Base cases and recursive calls

Subsets, permutations

N-Queens problem

Sudoku solver

Word search


6️⃣ Trees & Binary Trees

Traversals (Inorder, Preorder, Postorder)

Height and Diameter

Balanced Binary Tree

Lowest Common Ancestor (LCA)

Serialize & Deserialize Tree


7️⃣ Binary Search Trees (BST)

Search, Insert, Delete

Validate BST

Kth smallest/largest element

Convert BST to DLL


8️⃣ Heaps & Priority Queues

Min Heap / Max Heap

Heapify

Top K elements

Merge K sorted lists

Median in a stream


9️⃣ Graphs

Representations (adjacency list/matrix)

DFS, BFS

Cycle detection (directed & undirected)

Topological Sort

Dijkstra’s & Bellman-Ford algorithm

Union-Find (Disjoint Set)


10️⃣ Dynamic Programming (DP)

0/1 Knapsack

Longest Common Subsequence

Matrix Chain Multiplication

DP on subsequences

Memoization vs Tabulation


11️⃣ Greedy Algorithms

Activity selection

Huffman coding

Fractional knapsack

Job scheduling


12️⃣ Tries

Insert and search a word

Word search

Auto-complete feature


13️⃣ Bit Manipulation

XOR, AND, OR basics

Check if power of 2

Single Number problem

Count set bits

Coding Interview Resources: https://whatsapp.com/channel/0029VammZijATRSlLxywEC3X

ENJOY LEARNING 👍👍
4
Learning Python in 2025 is like discovering a treasure chest 🎁 full of magical powers! Here's why it's valuable:

1. Versatility 🌟: Python is used in web development, data analysis, artificial intelligence, machine learning, automation, and more. Whatever your interest, Python has an option for it.

2. Ease of Learning 📚: Python's syntax is as clear as a sunny day!☀️ Its simple and readable syntax makes it beginner-friendly, perfect for aspiring programmers of all levels.

3. Community Support 🤝: Python has a vast community of programmers ready to help! Whether you're stuck on a problem or looking for guidance, there are countless forums, tutorials, and resources to tap into.

4. Job Opportunities 💼: Companies are constantly seeking Python wizards to join their ranks! From tech giants to startups, the demand for Python skills is abundant.🔥

5. Future-proofing 🔮: With its widespread adoption and continuous growth, learning Python now sets you up for success in the ever-evolving world of tech.

6. Fun Projects 🎉: Python makes coding feel like brewing potions! From creating games 🎮 to building robots 🤖, the possibilities are endless.

So grab your keyboard and embark on a Python adventure! It's not just learning a language, it's unlocking a world of endless possibilities.
2
Is DSA important for interviews?

Yes, DSA (Data Structures and Algorithms) is very important for interviews, especially for software engineering roles.

I often get asked, What do I need to start learning DSA?

Here's the roadmap for getting started with Data Structures and Algorithms (DSA):

𝗣𝗵𝗮𝘀𝗲 𝟭: 𝗙𝘂𝗻𝗱𝗮𝗺𝗲𝗻𝘁𝗮𝗹𝘀
1. Introduction to DSA
- Understand what DSA is and why it's important.
- Overview of complexity analysis (Big O notation).

2. Complexity Analysis
- Time Complexity
- Space Complexity

3. Basic Data Structures
- Arrays
- Linked Lists
- Stacks
- Queues

4. Basic Algorithms
- Sorting (Bubble Sort, Selection Sort, Insertion Sort)
- Searching (Linear Search, Binary Search)

5. OOP (Object-Oriented Programming)

𝗣𝗵𝗮𝘀𝗲 𝟮: 𝗜𝗻𝘁𝗲𝗿𝗺𝗲𝗱𝗶𝗮𝘁𝗲 𝗖𝗼𝗻𝗰𝗲𝗽𝘁𝘀
1. Two Pointers Technique
- Introduction and basic usage
- Problems: Pair Sum, Triplets, Sorted Array Intersection etc..

2. Sliding Window Technique
- Introduction and basic usage
- Problems: Maximum Sum Subarray, Longest Substring with K Distinct Characters, Minimum Window Substring etc..

3. Line Sweep Algorithms
- Introduction and basic usage
- Problems: Meeting Rooms II, Skyline Problem

4. Recursion

5. Backtracking

6. Sorting Algorithms
- Merge Sort
- Quick Sort

7. Data Structures
- Hash Tables
- Trees (Binary Trees, Binary Search Trees)
- Heaps

𝗣𝗵𝗮𝘀𝗲 𝟯: 𝗔𝗱𝘃𝗮𝗻𝗰𝗲𝗱 𝗖𝗼𝗻𝗰𝗲𝗽𝘁𝘀
1. Graph Algorithms
- Graph Representation (Adjacency List, Adjacency Matrix)
- BFS (Breadth-First Search)
- DFS (Depth-First Search)
- Shortest Path Algorithms (Dijkstra's, Bellman-Ford)
- Minimum Spanning Tree (Kruskal's, Prim's)

2. Dynamic Programming
- Basic Problems (Fibonacci, Knapsack etc..)
- Advanced Problems (Longest Increasing Subsea mice, Matrix Chain Subsequence, Multiplication etc..)

3. Advanced Trees
- AVL Trees
- Red-Black Trees
- Segment Trees
- Trie

𝗣𝗵𝗮𝘀𝗲 𝟰: 𝗣𝗿𝗮𝗰𝘁𝗶𝗰𝗲 𝗮𝗻𝗱 𝗔𝗽𝗽𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻
1. Competitive Programming Platforms: LeetCode, Codeforces, HackerRank, CodeChef Solve problems daily

2. Mock Interviews
- Participate in mock interviews to simulate real interview scenarios.
- DSA interviews assess your ability to break down complex problems into smaller steps.

Best DSA RESOURCES: https://topmate.io/coding/886874

All the best 👍👍
2👍1
Preparing for a ReactJS interview? Here are some frequently asked questions to help you ace it!

🔹 What is React? Explain its core concepts, including JSX, virtual DOM, and component-based architecture.

🔹 Difference between functional and class components? Dive into hooks vs lifecycle methods.

🔹 What are hooks? Discuss useState, useEffect, and custom hooks.

🔹 Props vs State? Understand the difference and when to use each.

🔹 What is Redux? Know how to manage global state using Redux.

🔹 What are Higher-Order Components (HOCs)? Explain their role in component reusability.

🔹 What is lazy loading? Discuss the benefits of code splitting.

💡 Tip: Always relate these concepts to real-world projects you’ve worked on!

Web Development Best Resources: https://topmate.io/coding/930165

ENJOY LEARNING 👍👍
1
Typical C++ interview questions sorted by experience

Junior:
- What are the key features of object-oriented programming in C++?
- Explain the differences between public, private, and protected access specifiers in C++.
- Distinguish between function overloading and overriding in C++.
- Compare and contrast abstract classes and interfaces in C++.
- Can an interface inherit from another interface in C++?
- Define the static keyword in C++ and its significance.
- Is it possible to override a static method in C++?
- Explain the concepts of polymorphism and inheritance in C++.
- Can constructors be inherited in C++?
- Discuss pass-by-reference and pass-by-value for objects in C++.
- Compare == and .equals for string comparison in C++.
- Explain the purposes of the hashCode() and equals() functions.
- What does the Serializable interface do? How is it related to Parcelable in Android?
- Differentiate between Array and ArrayList in C++. When would you use each?
- Explain the distinction between Integer and int in C++.
- Define ThreadPool and discuss its advantages over using simple threads.
- Differentiate between local, instance, and class variables in C++.

Mid:
- What is reflection in C++?
- Define dependency injection and name a few libraries. Have you used any?
- Explain strong, soft, and weak references in C++.
- Interpret the meaning of the synchronized keyword.
- Can memory leaks occur in C++?
- Is it necessary to set references to null in C++?
- Why is a String considered immutable?
- Discuss transient and volatile modifiers in C++.
- What is the purpose of the finalize() method?
- How does the try{} finally{} block work in C++?
- Explain the difference between object instantiation and initialization.
- Under what conditions is a static block executed in C++?
- Why are generics used in C++?
- Mention some design patterns you are familiar with. Which do you typically use?
- Name some types of testing methodologies in C++.

Senior:
- Explain how std::stoi (string to integer) works in C++.
- What is the "double-check locking" problem, and how can it be solved in C++?
- Differentiate between StringBuffer and StringBuilder in C++.
- How is StringBuilder implemented to avoid the immutable string allocation problem?
- Explain the purpose of the Class.forName method in C++.
- Define Autoboxing and Unboxing in C++.
- What's the difference between Enumeration and Iterator in C++?
- Explain the difference between fail-fast and fail-safe in C++.
- What is PermGen in C++?
- Describe a Java priority queue.
- How is performance influenced by using the same number in different types: Int, Double, and Float?
- Explain the concept of the Java Heap.
- What is a daemon thread?
- Can a dead thread be restarted in C++?

ENJOY LEARNING 👍👍
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Top Programming Frameworks on GitHub in 2025 👨🏻‍💻⚙️

🔷 React (234,369 stars)
🚀 Vue.js (208,671 stars)
📊 TensorFlow (~186,000 stars)
🔸 Angular (97,453 stars)
🔗 Django (83,095 stars)
💡 Svelte (82,163 stars)
🐍 Flask (69,300 stars)
Express.js (66,702 stars)
🦄 Laravel (~57,800 stars)
🛠️ Spring Framework (~57,800 stars)
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🖥 VS Code Themes You Should Try
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