Daily Coding Challenges & Projects

Frontend Mini Project Challenge

Theme : JavaScript Logical Puzzles & Debugging

Challenge :

Write a function findMissingNumber(arr) that, given an array of unique integers from 1 to n with exactly one number missing, returns the missing value.

// e.g. findMissingNumber([1,2,4,5]) ➞ 3
function findMissingNumber(arr) {
  // your code here
}

Hints :

• Use Gauss’ formula (sum formula) or XOR operations.
• Ensure it works in O(n) time with O(1) extra space.

Try it live on CodeSandbox or JSFiddle!

Backend Challenge

Language Focus : C, C++, C#

Problem : Implement a CLI tool that reads numbers (one per line) from stdin and calculates their cumulative average after each input. Continue until EOF.

Bonus: Add dynamic memory handling and support floats.

Database Query Challenge

Problems on SQL - HR Database :

1. List employees hired within the past 6 months, showing name, hire date, and department.
2. Retrieve departments where no salary raises occurred in the last year.

Data Structures & Algorithms Challenge

• Easy:
• Problem : Reverse a singly linked list.
• Hint :Use three pointers (prev, current, next).
• Medium:
• Problem : Given a binary tree, return its level-order traversal (breadth-first).
• Hint :Use a queue to track nodes level by level.
• Hard:
• Problem : Given an array of intervals, merge overlapping ones.
• Hint :Sort by start time, then merge sequentially.

Bug of the Day

Language Focus :

Language : C

Buggy Code:

#include 

int main() {
  char *s = "hello";
  s[0] = 'H';
  printf("%s\n", s);
  return 0;
}

Task :Identify and fix the error.

Hint :String literals are immutable.

📋 Daily Micro-Project

Frontend Focus :

Project :

Build : A dynamic CSS-only loading spinner

• Use CSS animations/keyframes, no JS required.
• Make it responsive and centered.

Bonus : Let users toggle spinner color via CSS variables.

Trivia: 5 Fun Facts

1. The first computer programmer was Ada Lovelace in the 1800s.
2. The first high level language was Fortran, released in 1957.
3. Git (2005) was created by Linus Torvalds to manage Linux kernel development.
4. JavaScript was originally named Mocha, then LiveScript.
5. The first smartphone (IBM Simon, 1994) included email and apps—way before the iPhone.

Tool & Resource of the Day

Tool : Prettier

A code formatter for JavaScript, TypeScript, CSS, etc., that enforces consistent style.

Resource Roundup :

• "Clean Code" by Robert C. Martin (eBook)
• JavaScript: The Definitive Guide (MDN online)
• VSCode Shortcuts Cheat Sheet (PDF link)

Interview Question of the Day

Daily Interview Questions

Frontend :
1. Explain event bubbling vs event capturing in the DOM.
2. What are the pros and cons of CSS Grid vs Flexbox?
3. How does JavaScript’s event loop work?
4. What are mixins in Vue.js and when to use them?

Backend :
1. Explain the difference between pass-by-value and pass-by-reference.
2. How does garbage collection work in C#?
3. Describe mutex vs semaphore and use-cases.
4. How would you implement pagination in a REST API?

Database ( SQL ) :
1. What is the difference between WHERE and HAVING?
2. Explain normalization and its normal forms (1NF, 2NF, 3NF).
3. What’s the difference between COUNT(*) and COUNT(column)?

Others :
1. What are the main components of TCP handshake?
2. What is serverless architecture, and how does AWS Lambda fit in?

Daily Quiz Challenge

Frontend Quiz :

1. What does display: block; do in CSS?
2. Which Vue directive is used to loop through an array (v-for/v-if)?
3. Identify the output:

console.log(typeof null);

Backend Quiz :

1. Default port for PostgreSQL?
2. What does const mean in C++?
3. How does async/await simplify asynchronous JavaScript?

Others :

1. Explain the use of JOIN vs UNION.
2. What is a RESTful API?

Weekly Cross-Domain Activities ( June 20 to June 26, 2025 )

API of the Day:

Task : Integrate the News API to fetch top headlines based on user-selected categories.

Bonus :Add search and filter by country or keyword.

Linux/DevOps Tip :

Title : Monitor Server Resources

Commands :

• top – Live process monitoring
• df -h – Disk space usage
• free -m – Memory usage
• uptime – Server load
• lsof – Open files

Real-World Project of the Week ( June 20 to June 26, 2025 )

Project of the Week:

Build a Resume Builder Web App

• Tech Stack: HTML, CSS, JavaScript (React optional)
• Features: Section-wise input (Education, Experience, Skills), Live Preview, Download as PDF

Collaborative Project:

Idea : Open-source a Daily Code Challenge Tracker

• Use GitHub Projects or issues to track challenges.
• Allow contributors to submit PRs for daily code solutions.

Case Study:

How Netflix Handles Streaming at Scale

• Topics: CDN, Microservices, Chaos Engineering
• Activity: Recreate a mini Netflix UI with static video thumbnails and categories using React or Vue.