Here are the 5 SQL questions you can practice this weekend.



1. Write an SQL query to show, for each segment, the total number of users and the number of users who booked a flight in April 2022.

2. Write a query to identify users whose first booking was a hotel booking.

3. Write a query to calculate the number of days between the first and last booking of the user with user_id = 1.

4. Write a query to count the number of flight and hotel bookings in each user segment for the year 2022.

5. Find, for each segment, the user who made the earliest booking in April 2022, and also return how many total bookings that user made in April 2022.

create table booking_table (
booking_id varchar(10),
booking_date date,
user_id varchar(10),
line_of_business varchar(20)
);

insert into booking_table (booking_id, booking_date, user_id, line_of_business) values
('b1', '2022-03-23', 'u1', 'Flight'),
('b2', '2022-03-27', 'u2', 'Flight'),
('b3', '2022-03-28', 'u1', 'Hotel'),
('b4', '2022-03-31', 'u4', 'Flight'),
('b5', '2022-04-02', 'u1', 'Hotel'),
('b6', '2022-04-02', 'u2', 'Flight'),
('b7', '2022-04-06', 'u5', 'Flight'),
('b8', '2022-04-06', 'u6', 'Hotel'),
('b9', '2022-04-06', 'u2', 'Flight'),
('b10', '2022-04-10', 'u1', 'Flight'),
('b11', '2022-04-12', 'u4', 'Flight'),
('b12', '2022-04-16', 'u1', 'Flight'),
('b13', '2022-04-19', 'u2', 'Flight'),
('b14', '2022-04-20', 'u5', 'Hotel'),
('b15', '2022-04-22', 'u6', 'Flight'),
('b16', '2022-04-26', 'u4', 'Hotel'),
('b17', '2022-04-28', 'u2', 'Hotel'),
('b18', '2022-04-30', 'u1', 'Hotel'),
('b19', '2022-05-04', 'u4', 'Hotel'),
('b20', '2022-05-06', 'u1', 'Flight');

create table user_table (
user_id varchar(10),
segment varchar(10)
);

insert into user_table (user_id, segment) values
('u1', 's1'),
('u2', 's1'),
('u3', 's1'),
('u4', 's2'),
('u5', 's2'),
('u6', 's3'),
('u7', 's3'),
('u8', 's3'),
('u9', 's3'),
('u10', 's3');

✅ Top Programming Basics Interview Questions with Answers 🧠💻

1️⃣ What is a variable?
Answer:
A variable is a named container used to store data in a program. Its value can change during execution.
Example:

name = "Alice"
age = 25

2️⃣ What are data types?
Answer:
Data types define the kind of value a variable can hold. Common types:
– int: Integer (e.g., 5)
– float: Decimal (e.g., 3.14)
– char / str: Character or String
– bool: Boolean (True/False)

3️⃣ What are operators in programming?
Answer:
Operators perform operations on variables/values.
– Arithmetic: +, -, *, /
– Comparison: ==,!=, >, <
– Logical: &&, ||,! (or and, or, not)
– Assignment: =, +=, -=

4️⃣ What is type casting?
Answer:
Type casting means converting one data type to another.
Example (Python):

x = int("5")     # Converts string to integer

5️⃣ What is the purpose of comments in code?
Answer:
Comments are used to explain code. They're ignored during execution.
– Single-line: // comment or # comment
– Multi-line:

"""
This is a
multi-line comment
"""

6️⃣ How do you take input and display output?
Answer:
Python Example:

name = input("Enter your name: ")
print("Hello", name)

C++ Example:

cin >> name;
cout << "Hello " << name;

7️⃣ What is the difference between a statement and an expression?
Answer:
– Expression: Returns a value (e.g., 2 + 3)
– Statement: Performs an action (e.g., x = 5)

8️⃣ What is the difference between compile-time and run-time?
Answer:
– Compile-time: Errors detected before execution (e.g., syntax errors)
– Run-time: Errors during execution (e.g., divide by zero)

💬 Double Tap ❤️ for more!

⚡ 25 Browser Extensions to Supercharge Your Coding Workflow 🚀

✅ JSON Viewer
✅ Octotree (GitHub code tree)
✅ Web Developer Tools
✅ Wappalyzer (tech stack detector)
✅ React Developer Tools
✅ Redux DevTools
✅ Vue js DevTools
✅ Angular DevTools
✅ ColorZilla
✅ WhatFont
✅ CSS Peeper
✅ Axe DevTools (accessibility)
✅ Page Ruler Redux
✅ Lighthouse
✅ Check My Links
✅ EditThisCookie
✅ Tampermonkey
✅ Postman Interceptor
✅ RESTED
✅ GraphQL Playground
✅ XPath Helper
✅ Gitpod Browser Extension
✅ Codeium for Chrome
✅ TabNine Assistant
✅ Grammarly (for cleaner docs & commits)

🔥 React ❤️ if you’re using at least one of these!

💡 10 Smart Programming Habits Every Developer Should Build 👨‍💻🧠

1️⃣ Write clean, readable code
→ Code is read more often than it’s written. Clarity > cleverness.

2️⃣ Break big problems into small parts
→ Divide and conquer. Small functions are easier to debug and reuse.

3️⃣ Use meaningful commit messages
→ “Fixed stuff” doesn’t help. Be specific: “Fix null check on login form.”

4️⃣ Keep learning new tools & languages
→ Tech evolves fast. Stay curious and adaptable.

5️⃣ Write tests, even basic ones
→ Prevent future bugs. Start with simple unit tests.

6️⃣ Use a linter and formatter
→ Tools like ESLint, Black, or Prettier keep your code clean automatically.

7️⃣ Document your code
→ Write docstrings or inline comments to explain logic clearly.

8️⃣ Review your code before pushing
→ Catch silly mistakes early. Think of it as proofreading your code.

9️⃣ Optimize only when needed
→ First make it work, then make it fast.

🔟 Contribute to open source or side projects
→ Practice, network, and learn from real-world codebases.

💬 Tap ❤️ if you found this helpful!

12 Websites to Learn Programming for FREE🧑‍💻

✅ freecodecamp ❤️
✅ javascript 👍🏻
✅ theodinproject 👏🏻
✅ stackoverflow 🫶🏻
✅ geeksforgeeks 😍
✅ khanacademy 🫣
✅ javatpoint ⚡
✅ codecademy 🫡
✅ sololearn ✌🏻
✅ programiz ⭐
✅ w3school 🙌🏻
✅ youtube 🥰

Which one is your favourite!
Give reaction❤️

⚡️ 25 Browser Extensions to Supercharge Your Coding Workflow 🚀

✅ JSON Viewer
✅ Octotree (GitHub code tree)
✅ Web Developer Tools
✅ Wappalyzer (tech stack detector)
✅ React Developer Tools
✅ Redux DevTools
✅ Vue js DevTools
✅ Angular DevTools
✅ ColorZilla
✅ WhatFont
✅ CSS Peeper
✅ Axe DevTools (accessibility)
✅ Page Ruler Redux
✅ Lighthouse
✅ Check My Links
✅ EditThisCookie
✅ Tampermonkey
✅ Postman Interceptor
✅ RESTED
✅ GraphQL Playground
✅ XPath Helper
✅ Gitpod Browser Extension
✅ Codeium for Chrome
✅ TabNine Assistant
✅ Grammarly (for cleaner docs & commits)

🔥 React ❤️ if you’re using at least one of these!

✅ DSA Interview Questions & Answers – Part 1 🧠💻

1️⃣ What is a Data Structure?
A: A way to store and organize data for efficient access and modification. Examples: Array, Linked List, Stack, Queue, Tree, Graph.

2️⃣ What is the difference between Array and Linked List?
A:
⦁ Array: Fixed size, contiguous memory, fast random access (O(1)), slow insertion/deletion (O(n)).
⦁ Linked List: Dynamic size, nodes in memory connected via pointers, slower access (O(n)), fast insertion/deletion (O(1)) at head or tail.

3️⃣ What is a Stack? Give an example.
A: Stack is a linear data structure following LIFO (Last In First Out).
⦁ Operations: push, pop, peek
⦁ Example: Browser history, Undo functionality in editors.

4️⃣ What is a Queue? Difference between Queue & Stack?
A: Queue is a linear data structure following FIFO (First In First Out).
⦁ Stack: LIFO → Last element added is first to remove.
⦁ Queue: FIFO → First element added is first to remove.
⦁ Example: Print job scheduling, Task scheduling.

5️⃣ What is a Linked List? Types?
A: Linked List is a collection of nodes where each node contains data and a pointer to the next node.
⦁ Types:
⦁ Singly Linked List
⦁ Doubly Linked List
⦁ Circular Linked List

6️⃣ What is the difference between Stack and Heap memory?
A:
⦁ Stack: Stores local variables, function calls; LIFO; automatically managed; faster access.
⦁ Heap: Stores dynamic memory; managed manually or via garbage collection; slower access; flexible size.

7️⃣ What is a Hash Table?
A: A data structure that maps keys to values using a hash function for O(1) average-time access.
⦁ Example: Python dict, Java HashMap.
⦁ Collision Handling: Chaining, Open addressing.

8️⃣ What is the difference between BFS and DFS?
A:
⦁ BFS (Breadth-First Search): Level-wise traversal; uses Queue; finds shortest path in unweighted graphs.
⦁ DFS (Depth-First Search): Deep traversal using Stack/Recursion; uses less memory for sparse graphs.

9️⃣ What is a Binary Search Tree (BST)?
A: A tree where each node:
⦁ Left child < Node < Right child
⦁ Allows O(log n) search, insertion, and deletion on average.
⦁ Not necessarily balanced → worst-case O(n).

🔟 What is Time Complexity?
A: Measure of the number of operations an algorithm takes relative to input size (n).
⦁ Examples:
⦁ O(1) → Constant
⦁ O(n) → Linear
⦁ O(log n) → Logarithmic
⦁ O(n²) → Quadratic

💬 Double Tap ❤️ if you found this helpful!

✅ DSA Interview Questions & Answers – Part 2 🧠💻

1️⃣ What is a Graph?
A: A non-linear data structure with nodes (vertices) connected by edges representing relationships.
⦁ Types: Directed (one-way edges, like Twitter follows), Undirected (bidirectional, like friendships), Weighted (edges with costs, e.g., distances), Unweighted.
⦁ Example: Social networks (users as nodes, connections as edges) or maps (cities and routes)—BFS/DFS traversal is key for shortest paths.

2️⃣ Difference between Tree and Graph?
A:
⦁ Tree: Acyclic (no loops), connected graph with exactly one path between nodes, hierarchical with a root and N-1 edges for N nodes—great for file systems.
⦁ Graph: Can have cycles, multiple paths, disconnected components, and more edges—more flexible but needs cycle detection algorithms like DFS.

3️⃣ What is a Heap?
A: A complete binary tree satisfying the heap property for fast min/max access.
⦁ Max Heap: Parent nodes ≥ children (root is maximum).
⦁ Min Heap: Parent ≤ children (root is minimum).
⦁ Uses: Priority queues (e.g., task scheduling), Heap Sort (O(n log n))—implemented via arrays for efficiency.

4️⃣ What is Recursion? Example?
A: A technique where a function solves a problem by calling itself on smaller inputs until a base case stops it, using implicit stack.
⦁ Example: Factorial: def fact(n): return 1 if n <= 1 else n * fact(n-1). Also Fibonacci or tree traversals—watch for stack overflow on deep calls.

5️⃣ Difference between Recursion and Iteration?
A:
⦁ Recursion: Self-calling with base case, elegant for tree/graph problems but uses call stack (risk of overflow), O(n) space.
⦁ Iteration: Uses loops (for/while), explicit control, lower memory, faster execution—convert recursion via tail optimization for interviews.

6️⃣ What is a Trie?
A: A prefix tree for storing strings in a tree where each node represents a character, enabling fast lookups and prefixes.
⦁ Use Case: Autocomplete (search engines), spell checkers, IP routing—O(m) time for m-length word, space-efficient for common prefixes.

7️⃣ Difference between Linear Search & Binary Search?
A:
⦁ Linear Search: Scans sequentially, O(n) time, works on unsorted data—simple but inefficient for large lists.
⦁ Binary Search: Divides sorted array in half repeatedly, O(log n) time—requires sorted input, ideal for databases or sorted arrays.

8️⃣ What is a Circular Queue?
A: A queue implementation where the rear connects back to front, reusing space to avoid linear queue's "wasted" slots after dequeues.
⦁ Efficient memory usage (no shifting), fixed size, handles wrap-around with modulo—common in buffering systems like OS task queues.

9️⃣ What is a Priority Queue?
A: An abstract data type where elements have priorities; dequeue removes highest/lowest priority first (not FIFO).
⦁ Implemented using: Heaps (binary for O(log n) insert/extract), also arrays or linked lists—used in Dijkstra's algorithm or job scheduling.

🔟 What is Dynamic Programming (DP)?
A: An optimization technique for problems with overlapping subproblems and optimal substructure, solving bottom-up or top-down with memoization to avoid recomputation.
⦁ Example: Fibonacci (store fib(n-1) + fib(n-2)), 0/1 Knapsack (max value without exceeding weight)—reduces exponential to polynomial time.

💬 Double Tap ❤️ if this helped you!

Join our WhatsApp channel for free Python Programming Resources
👇👇
https://whatsapp.com/channel/0029VaiM08SDuMRaGKd9Wv0L

Big-O Cheatsheet👨🏻‍💻📝

React ❤️ for more like this

Step-by-step Guide to Create a Web Development Portfolio:

✅ 1️⃣ Choose Your Tech Stack
Decide what type of web developer you are:
• Frontend → HTML, CSS, JavaScript, React
• Backend → Node.js, Express, Python (Django/Flask)
• Full-stack → Mix of both frontend + backend
• Optional: Use tools like Git, GitHub, Netlify, Vercel

✅ 2️⃣ Plan Your Portfolio Structure
Your site should include:
• Home Page – Short intro about you
• About Me – Skills, tools, background
• Projects – Showcased with live links + GitHub
• Contact – Email, LinkedIn, social media links
• Optional: Blog section (for SEO & personal branding)

✅ 3️⃣ Build the Portfolio Website
Use these options:
• HTML/CSS/JS (for full control)
• React or Vue (for interactive UI)
• Use templates from GitHub for inspiration
• Responsive design: Make sure it works on mobile too!

✅ 4️⃣ Add 2–4 Strong Projects
Projects should be diverse and show your skills:
• Personal website
• Weather app, to-do list, blog, portfolio CMS
• E-commerce or booking clone
• API integration project

Each project should have:
• Short description
• Tech stack used
• Live demo link
• GitHub code link
• Screenshots or GIFs

✅ 5️⃣ Deploy Your Portfolio Online
Use free hosting platforms:
• Netlify
• GitHub Pages
• Vercel
• Render

✅ 6️⃣ Keep It Updated
• Add new projects
• Keep links working
• Fix any bugs
• Write short blog posts if possible

💡 Pro Tips
• Make your site visually clean and simple
• Add a downloadable resume
• Link your GitHub and LinkedIn
• Use a custom domain if possible (e.g., yourname.dev)

🎯 Goal: When someone visits your site, they should know who you are, what you do, and how to contact you—all in under 30 seconds.

👍 Tap ❤️ if you found this helpful!

The program for the 10th AI Journey 2025 international conference has been unveiled: scientists, visionaries, and global AI practitioners will come together on one stage. Here, you will hear the voices of those who don't just believe in the future—they are creating it!

Speakers include visionaries Kai-Fu Lee and Chen Qufan, as well as dozens of global AI gurus from around the world!

On the first day of the conference, November 19, we will talk about how AI is already being used in various areas of life, helping to unlock human potential for the future and changing creative industries, and what impact it has on humans and on a sustainable future.

On November 20, we will focus on the role of AI in business and economic development and present technologies that will help businesses and developers be more effective by unlocking human potential.

On November 21, we will talk about how engineers and scientists are making scientific and technological breakthroughs and creating the future today!

Ride the wave with AI into the future!

Tune in to the AI Journey webcast on November 19-21.

🧑‍💻 How to Crack Coding Interviews in 2025 💥🚀

1️⃣ Understand the Interview Format
⦁ Phone screen, technical rounds, system design, behavioral
⦁ Research company-specific patterns on sites like Glassdoor

2️⃣ Master Data Structures & Algorithms
⦁ Arrays, Strings, Linked Lists, Trees, Graphs
⦁ Sorting, Searching, Recursion, Dynamic Programming
⦁ Practice daily on LeetCode, HackerRank, Codeforces

3️⃣ Learn Problem-Solving Patterns
⦁ Sliding window, Two pointers, Fast & slow pointers
⦁ Backtracking, Greedy, Divide & Conquer
⦁ Understand when & how to apply them

4️⃣ Write Clean & Efficient Code
⦁ Focus on readability, naming, and edge cases
⦁ Optimize time & space complexity
⦁ Explain your approach clearly during interviews

5️⃣ Mock Interviews & Peer Coding
⦁ Practice with friends or platforms like Pramp, Interviewing.io
⦁ Get comfortable thinking aloud and receiving feedback

6️⃣ Prepare for Behavioral Questions
⦁ Use STAR method (Situation, Task, Action, Result)
⦁ Highlight teamwork, problem-solving, and adaptability

7️⃣ Know Your Projects & Resume
⦁ Be ready to explain your role, challenges, and learnings
⦁ Discuss tech stack and decisions confidently

8️⃣ Stay Calm & Confident
⦁ Take a deep breath before coding
⦁ Think aloud, clarify doubts
⦁ It’s okay to ask for hints or discuss trade-offs

💬 Double Tap ❤️ For More!

Tune in to the 10th AI Journey 2025 international conference: scientists, visionaries, and global AI practitioners will come together on one stage. Here, you will hear the voices of those who don't just believe in the future—they are creating it!

Speakers include visionaries Kai-Fu Lee and Chen Qufan, as well as dozens of global AI gurus! Do you agree with their predictions about AI?

On the first day of the conference, November 19, we will talk about how AI is already being used in various areas of life, helping to unlock human potential for the future and changing creative industries, and what impact it has on humans and on a sustainable future.

On November 20, we will focus on the role of AI in business and economic development and present technologies that will help businesses and developers be more effective by unlocking human potential.

On November 21, we will talk about how engineers and scientists are making scientific and technological breakthroughs and creating the future today! The day's program includes presentations by scientists from around the world:
- Ajit Abraham (Sai University, India) will present on “Generative AI in Healthcare”
- Nebojša Bačanin Džakula (Singidunum University, Serbia) will talk about the latest advances in bio-inspired metaheuristics
- AIexandre Ferreira Ramos (University of São Paulo, Brazil) will present his work on using thermodynamic models to study the regulatory logic of transcriptional control at the DNA level
- Anderson Rocha (University of Campinas, Brazil) will give a presentation entitled “AI in the New Era: From Basics to Trends, Opportunities, and Global Cooperation”.

And in the special AIJ Junior track, we will talk about how AI helps us learn, create and ride the wave with AI.

The day will conclude with an award ceremony for the winners of the AI Challenge for aspiring data scientists and the AIJ Contest for experienced AI specialists. The results of an open selection of AIJ Science research papers will be announced.

Ride the wave with AI into the future!

Tune in to the AI Journey webcast on November 19-21.

Top 50 Coding Interview Questions 💻🚀

1. What is the time and space complexity of your code?
2. Difference between array and linked list.
3. How does a HashMap work internally?
4. What is recursion? Give an example.
5. Explain stack vs. queue.
6. What is a binary search and when to use it?
7. Difference between BFS and DFS.
8. What is dynamic programming?
9. Solve Fibonacci using memoization.
10. Explain two-pointer technique with an example.
11. What is a sliding window algorithm?
12. Detect cycle in a linked list.
13. Find the intersection of two arrays.
14. Reverse a string or linked list.
15. Check if a string is a palindrome.
16. What are the different sorting algorithms?
17. Explain quicksort vs. mergesort.
18. What is a binary search tree (BST)?
19. Inorder, Preorder, Postorder traversals.
20. Implement LRU Cache.
21. Find the longest substring without repeating characters.
22. Explain backtracking with N-Queens problem.
23. What is a trie? Where is it used?
24. Explain bit manipulation tricks.
25. Kadane’s Algorithm for maximum subarray sum.
26. What are heaps and how do they work?
27. Find kth largest element in an array.
28. How to detect cycle in a graph?
29. Topological sort of a DAG.
30. Implement a stack using queues.
31. Explain the difference between pass by value and reference.
32. What is memoization vs. tabulation?
33. Solve the knapsack problem.
34. Find duplicate numbers in an array.
35. What are function closures in Python/JavaScript?
36. How does garbage collection work in Java?
37. What are lambda functions?
38. Explain OOPs concepts: Inheritance, Polymorphism, Encapsulation, Abstraction.
39. What is multithreading vs. multiprocessing?
40. Difference between process and thread.
41. Implement a binary heap.
42. Explain prefix sum technique.
43. Design a parking lot system.
44. Find median in a stream of numbers.
45. Detect anagram strings.
46. Serialize and deserialize a binary tree.
47. Implement a trie with insert and search.
48. Explain design patterns like Singleton, Factory.
49. Discuss trade-offs between readability and performance.
50. How do you debug a tricky bug?

💬 Tap ❤️ for detailed answers!

🔅 Python Function

Useful Free Resources To Crack Your Next Insterview
👇👇

Job Interviewing Skills Tutorial Free Course

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Interview Training for Hiring Managers and Teams Free Udemy course

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Coding Interview Prep Free course by Freecodecamp

https://www.freecodecamp.org/learn/coding-interview-prep/

Cracking the coding interview free book

https://t.me/crackingthecodinginterview/272

Python Interview Question and Answers for freshers

https://www.careerride.com/python-interview-questions.aspx

50 coding interview Questions book

https://www.byte-by-byte.com/wp-content/uploads/2019/01/50-Coding-Interview-Questions.pdf

Ultimate Guide to Machine Learning Interviews

https://t.me/datasciencefun/820

ENJOY LEARNING 👍👍