Daily Coding Challenges & Projects

Frontend Mini Project Challenge

Theme : CSS Animation Effects

Challenge :

Create a pulsing loader animation using only CSS.

• Three dots should scale up and down continuously.
• Use @keyframes and transform: scale().

Backend Challenge

Focus : Java, Kotlin

Java Challenge :

Write a Java program that simulates a basic task scheduler:

• Accepts tasks with priorities.
• Always executes the highest-priority task first.
• Use a PriorityQueue.

Kotlin Challenge :

Create a Kotlin program that:

• Reads a text file line by line.
• Counts the number of unique words.
• Prints the top 5 most frequent words.

Database Query Challenge

Problems on SQL - HR Database :

1. Write a query to find the top 3 highest-paid employees in each department.
2. Write a query to list employees who were hired before their managers.

Data Structures & Algorithms Challenge

• Easy:
• Problem : Given a string of parentheses "()[]{}", check if it is valid.
• Hint : Stack
• Medium:
• Problem : Find the peak element in an array (greater than its neighbors).
• Hint : Binary Search
• Hard:
• Problem : Word Break Problem – Given a string and a dictionary of words, check if the string can be segmented into dictionary words.
• Hint : DP + Backtracking

Bug of the Day

Focus : Java, Kotlin

Buggy Code ( Java ) :

public class Test {
    public static void main(String[] args) {
        String s = null;
        if(s.equals("hello")) {
            System.out.println("Hi");
        }
    }
}

Challenge: Find and fix the bug(s).

📋 Daily Micro-Project

Focus : Backend

Task :

Build a REST API endpoint in Java (Spring Boot) or Kotlin (Ktor) that:

• Accepts a POST /reverse request with a string in JSON.
• Returns the reversed string in JSON.

Trivia: 5 Fun Facts

1. The first version of Java was released in 1995 by Sun Microsystems.
2. Kotlin became an official Android language in 2017.
3. SQL was originally called SEQUEL (Structured English Query Language).
4. CSS animations were introduced in CSS3.
5. The name “Java” was inspired by Java coffee.

Tool & Resource of the Day

Tool : Docker

• Simplifies app deployment with containers.
• Ensures consistent environments across dev, test, and production.

Resource Roundup :

• Docker Official Docs
• Free course: Docker for Beginners

Interview Question of the Day

Daily Interview Questions

Frontend :
1. How does CSS position: sticky work?
2. Explain the difference between relative, absolute, and fixed positioning in CSS.
3. How does JavaScript’s event loop work?
4. What are the advantages of using CSS Grid over Flexbox?

Backend :
1. Explain the difference between checked and unchecked exceptions in Java.
2. What is the JVM, and how does it work?
3. How does Kotlin handle null safety compared to Java?
4. Explain the concept of coroutines in Kotlin.

Database :
1. What is the difference between a primary key and a unique key?
2. What is the difference between DELETE, TRUNCATE, and DROP in SQL?
3. Explain ACID properties in databases.

Others :
1. What is the difference between virtualization and containerization?
2. Explain what CI/CD pipelines are in DevOps.

Daily Quiz Challenge

Frontend :

1. Which CSS property controls text size?
• font-style
• font-size
• text-size
• text-style
2. Which JavaScript function is used to parse JSON strings?
• JSON.parse()
• JSON.stringify()
• parseInt()
• eval()
3. Which CSS property allows you to animate transitions smoothly?
• transition
• transform
• animation
• ease

Backend :

1. Which keyword in Java is used to inherit a class?
• implements
• extends
• inherits
• super
2. In Java, which collection guarantees uniqueness of elements?
• List
• Set
• Map
• Queue
3. In Kotlin, which keyword is used to define a coroutine?
• run
• suspend
• launch
• async

Database :

1. Which SQL statement is used to remove a table permanently?
• DROP TABLE
• DELETE TABLE
• REMOVE TABLE
• TRUNCATE TABLE

Other :

2. Who created Linux?
• Bill Gates
• Steve Jobs
• Linus Torvalds
• Ken Thompson

Mixed Quiz :

3. Which of the following is true?
• CSS cannot create animations.
• Java and Kotlin both run on JVM.
• SQL is case-sensitive for all keywords.
• Docker cannot run on Windows.

Weekly Cross-Domain Activities ( September 12 to September 18, 2025 )

API of the Day:

Integrate the NASA Astronomy Picture of the Day API and display today’s image.

Linux / DevOps Tip : Use df -h to check disk usage and du -sh for folder sizes.

Real-World Project of the Week ( September 12 to September 18, 2025 )

Project of the Week:

Build a habit tracker app ( Frontend: React/Vue + Backend: Node.js/Scala + DB: PostgreSQL).

Collaborative Project :

Join the open-source project FreeCodeCamp

Case Study :

Study how Netflix handles recommendations using collaborative filtering.