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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Types of Data Structures πŸ‘†
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Advanced SQL Optimization Tips for Data Analysts

Use Proper Indexing: Create indexes for frequently queried columns.

Avoid SELECT *: Specify only required columns to improve performance.

Use WHERE Instead of HAVING: Filter data early in the query.

Limit Joins: Avoid excessive joins to reduce query complexity.

Apply LIMIT or TOP: Retrieve only the required rows.

Optimize Joins: Use INNER JOIN over OUTER JOIN where applicable.

Use Temporary Tables: Break complex queries into smaller parts.

Avoid Functions on Indexed Columns: It prevents index usage.

Use CTEs for Readability: Simplify nested queries using Common Table Expressions.

Analyze Execution Plans: Identify bottlenecks and optimize queries.

Here you can find SQL Interview ResourcesπŸ‘‡
https://whatsapp.com/channel/0029VaGgzAk72WTmQFERKh02

Like this post if you need more πŸ‘β€οΈ

Share with credits: https://t.me/sqlspecialist

Hope it helps :)
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Web Development Interview Questions for Freshers

1. What happens when you type a URL in your browser and press Enter?
Answer:

DNS lookup happens to find the IP address

Browser sends an HTTP/HTTPS request to the server

Server processes and sends back HTML/CSS/JS

Browser renders the page using its rendering engine


2. What is the difference between GET and POST requests?
Answer:

GET: Sends data in the URL, used for fetching data

POST: Sends data in the body, used for submitting data securely


3. What is a responsive website?
Answer:
A responsive website adjusts layout and design based on screen size and device (mobile, tablet, desktop), usually using CSS media queries.

4. What is the role of Webpack in web development?
Answer:
Webpack bundles JavaScript files, CSS, and assets into optimized output for faster website loading and better performance.

5. What is the purpose of async and defer in script tags?
Answer:

async: Loads script asynchronously and executes it immediately

defer: Loads script asynchronously but executes after HTML is parsed


6. What is the difference between localStorage and sessionStorage?
Answer:

localStorage: Stores data with no expiration

sessionStorage: Stores data until the browser tab is closed


7. What is CORS?
Answer:
CORS (Cross-Origin Resource Sharing) is a browser security feature that restricts cross-domain API calls unless the server allows it.

8. What is the difference between null and undefined in JavaScript?
Answer:

undefined: A variable declared but not assigned a value

null: A variable explicitly set to have no value


9. How do you optimize website performance?
Answer:

Minify CSS/JS

Compress images

Use lazy loading

Use caching

Reduce HTTP requests

Use a CDN


10. What is the DOM?
Answer:
DOM (Document Object Model) represents the structure of an HTML document as objects, which JavaScript can interact with to change content dynamically.

Credits: https://whatsapp.com/channel/0029VaiSdWu4NVis9yNEE72z/847
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Want to get started with System design interview preparation, start with these πŸ‘‡

1. Learn to understand requirements
2. Learn the difference between horizontal and vertical scaling.
3. Study latency and throughput trade-offs and optimization techniques.
4. Understand the CAP Theorem (Consistency, Availability, Partition Tolerance).
5. Learn HTTP/HTTPS protocols, request-response lifecycle, and headers.
6. Understand DNS and how domain resolution works.
7. Study load balancers, their types (Layer 4 and Layer 7), and algorithms.
8. Learn about CDNs, their use cases, and caching strategies.
9. Understand SQL databases (ACID properties, normalization) and NoSQL types (key–value, document, graph).
10. Study caching tools (Redis, Memcached) and strategies (write-through, write-back, eviction policies).
11. Learn about blob storage systems like S3 or Google Cloud Storage.
12. Study sharding and horizontal partitioning of databases.
13. Understand replication (leader–follower, multi-leader) and consistency models.
14. Learn failover mechanisms like active-passive and active-active setups.
15. Study message queues like RabbitMQ, Kafka, and SQS.
16. Understand consensus algorithms such as Paxos and Raft.
17. Learn event-driven architectures, Pub/Sub models, and event sourcing.
18. Study distributed transactions (two-phase commit, sagas).
19. Learn rate-limiting techniques (token bucket, leaky bucket algorithms).
20. Study API design principles for REST, GraphQL, and gRPC.
21. Understand microservices architecture, communication, and trade-offs with monoliths.
22. Learn authentication and authorization methods (OAuth, JWT, SSO).
23. Study metrics collection tools like Prometheus or Datadog.
24. Understand logging systems (e.g., ELK stack) and tracing tools (OpenTelemetry, Jaeger).
25.Learn about encryption (data at rest and in transit) and rate-limiting for security.
26. And then practise the most commonly asked questions like URL shorteners, chat systems, ride-sharing apps, search engines, video streaming, and e-commerce websites

Coding Interview Resources: https://whatsapp.com/channel/0029VammZijATRSlLxywEC3X
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List of most asked Programming Interview Questions.

Are you preparing for a coding interview? This tweet is for you. It contains a list of the most asked interview questions from each topic.

Arrays

- How is an array sorted using quicksort?
- How do you reverse an array?
- How do you remove duplicates from an array?
- How do you find the 2nd largest number in an unsorted integer array?

Linked Lists

- How do you find the length of a linked list?
- How do you reverse a linked list?
- How do you find the third node from the end?
- How are duplicate nodes removed in an unsorted linked list?

Strings

- How do you check if a string contains only digits?
- How can a given string be reversed?
- How do you find the first non-repeated character?
- How do you find duplicate characters in strings?

Binary Trees

- How are all leaves of a binary tree printed?
- How do you check if a tree is a binary search tree?
- How is a binary search tree implemented?
- Find the lowest common ancestor in a binary tree?

Graph

- How to detect a cycle in a directed graph?
- How to detect a cycle in an undirected graph?
- Find the total number of strongly connected components?
- Find whether a path exists between two nodes of a graph?
- Find the minimum number of swaps required to sort an array.

Dynamic Programming

1. Find the longest common subsequence?
2. Find the longest common substring?
3. Coin change problem?
4. Box stacking problem?
5. Count the number of ways to cover a distance?
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Python Cheatsheet πŸš€

1️⃣ Variables & Data Types

x = 10 (Integer)

y = 3.14 (Float)

name = "Python" (String)

is_valid = True (Boolean)

items = [1, 2, 3] (List)

data = (1, 2, 3) (Tuple)

person = {"name": "Alice", "age": 25} (Dictionary)


2️⃣ Operators

Arithmetic: +, -, *, /, //, %, **

Comparison: ==, !=, >, <, >=, <=

Logical: and, or, not

Membership: in, not in


3️⃣ Control Flow

If-Else:

if age > 18:
print("Adult")
elif age == 18:
print("Just turned 18")
else:
print("Minor")

Loops:

for i in range(5):
print(i)
while x < 10:
x += 1


4️⃣ Functions

Defining & Calling:

def greet(name):
return f"Hello, {name}"
print(greet("Alice"))

Lambda Functions: add = lambda x, y: x + y


5️⃣ Lists & Dictionary Operations

Append: items.append(4)

Remove: items.remove(2)

List Comprehension: [x**2 for x in range(5)]

Dictionary Access: person["name"]


6️⃣ File Handling

Read File:

with open("file.txt", "r") as f:
content = f.read()

Write File:

with open("file.txt", "w") as f:
f.write("Hello, World!")


7️⃣ Exception Handling

try:
result = 10 / 0
except ZeroDivisionError:
print("Cannot divide by zero!")
finally:
print("Done")

8️⃣ Modules & Packages

Importing:

import math
print(math.sqrt(25))

Creating a Module (mymodule.py):

def add(x, y):
return x + y

Usage: from mymodule import add


9️⃣ Object-Oriented Programming (OOP)

Defining a Class:

class Person:
def init(self, name, age):
self.name = name
self.age = age
def greet(self):
return f"Hello, my name is {self.name}"

Creating an Object: p = Person("Alice", 25)


πŸ”Ÿ Useful Libraries

NumPy: import numpy as np

Pandas: import pandas as pd

Matplotlib: import matplotlib.pyplot as plt

Requests: import requests

Python Resources: https://whatsapp.com/channel/0029VaiM08SDuMRaGKd9Wv0L

ENJOY LEARNING πŸ‘πŸ‘
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πŸš€ Coding Projects & Ideas πŸ’»

Inspire your next portfolio project β€” from beginner to pro!

πŸ—οΈ Beginner-Friendly Projects

1️⃣ To-Do List App – Create tasks, mark as done, store in browser.
2️⃣ Weather App – Fetch live weather data using a public API.
3️⃣ Unit Converter – Convert currencies, length, or weight.
4️⃣ Personal Portfolio Website – Showcase skills, projects & resume.
5️⃣ Calculator App – Build a clean UI for basic math operations.

βš™οΈ Intermediate Projects

6️⃣ Chatbot with AI – Use NLP libraries to answer user queries.
7️⃣ Stock Market Tracker – Real-time graphs & stock performance.
8️⃣ Expense Tracker – Manage budgets & visualize spending.
9️⃣ Image Classifier (ML) – Classify objects using pre-trained models.
πŸ”Ÿ E-Commerce Website – Product catalog, cart, payment gateway.

πŸš€ Advanced Projects

1️⃣1️⃣ Blockchain Voting System – Decentralized & tamper-proof elections.
1️⃣2️⃣ Social Media Analytics Dashboard – Analyze engagement, reach & sentiment.
1️⃣3️⃣ AI Code Assistant – Suggest code improvements or detect bugs.
1️⃣4️⃣ IoT Smart Home App – Control devices using sensors and Raspberry Pi.
1️⃣5️⃣ AR/VR Simulation – Build immersive learning or game experiences.

πŸ’‘ Tip: Build in public. Share your process on GitHub, LinkedIn & Twitter.

πŸ”₯ React ❀️ for more project ideas!
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Backend Development – Essential Concepts πŸš€

1️⃣ Backend vs. Frontend

Frontend – Handles UI/UX (HTML, CSS, JavaScript, React, Vue).

Backend – Manages server, database, APIs, and business logic.


2️⃣ Backend Programming Languages

Python – Django, Flask, FastAPI.

JavaScript – Node.js, Express.js.

Java – Spring Boot.

PHP – Laravel.

Ruby – Ruby on Rails.

Go – Gin, Echo.


3️⃣ Databases

SQL Databases – MySQL, PostgreSQL, MS SQL, MariaDB.

NoSQL Databases – MongoDB, Firebase, Cassandra, DynamoDB.

ORM (Object-Relational Mapping) – SQLAlchemy (Python), Sequelize (Node.js).


4️⃣ APIs & Web Services

REST API – Uses HTTP methods (GET, POST, PUT, DELETE).

GraphQL – Flexible API querying.

WebSockets – Real-time communication.

gRPC – High-performance communication.


5️⃣ Authentication & Security

JWT (JSON Web Token) – Secure user authentication.

OAuth 2.0 – Third-party authentication (Google, Facebook).

Hashing & Encryption – Protecting user data (bcrypt, AES).

CORS & CSRF Protection – Prevent security vulnerabilities.


6️⃣ Server & Hosting

Cloud Providers – AWS, Google Cloud, Azure.

Serverless Computing – AWS Lambda, Firebase Functions.

Docker & Kubernetes – Containerization and orchestration.


7️⃣ Caching & Performance Optimization

Redis & Memcached – Fast data caching.

Load Balancing – Distribute traffic efficiently.

CDN (Content Delivery Network) – Faster content delivery.


8️⃣ DevOps & Deployment

CI/CD Pipelines – GitHub Actions, Jenkins, GitLab CI.

Monitoring & Logging – Prometheus, ELK Stack.

Version Control – Git, GitHub, GitLab.

Like it if you need a complete tutorial on all these topics! πŸ‘β€οΈ

Web Development Best Resources

ENJOY LEARNING πŸ‘πŸ‘
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Types of API βœ…
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