Daily Coding Challenges & Projects

Frontend Mini Project Challenge

CSS Animation Effects

Challenge :

Create a Bouncing Ball Animation using Pure CSS

• Animate a circle to bounce vertically.
• Use @keyframes and cubic-bezier easing for realistic effect.
• Bonus: Add a shadow that scales with bounce.

Try it online : CodePen playground ( you can pre-link your platform )

Backend Challenge

Java & Kotlin

Java Challenge :

Implement a Simple Rate Limiter in Java

• Limit: 5 requests per minute per user.
• Use HashMap<String, List<LocalDateTime>> to track access times.

Kotlin Challenge :

Kotlin Coroutines Task Queue

• Use coroutines to manage a queue of tasks.
• Simulate delayed execution using delay().

Database Query Challenge

Problems on SQL - HR Database :

1. Find employees whose salary is above the department average.
2. List departments with no managers assigned in the department table.

Data Structures & Algorithms Challenge

• Easy:
• Problem : Check if an array is a rotated sorted array.
• Hint : Look for the point of inflection where order breaks.
• Medium:
• Problem : Longest substring with at most 2 distinct characters.
• Hint : Use sliding window + HashMap to track character frequency.
• Hard:
• Problem : Find all palindromic partitions of a string.
• Hint : Use backtracking with palindrome check memoization.

Bug of the Day

Language Focus : Java

Java Bug:

Buggy Code:

public class Main {
    public static void main(String[] args) {
        String s = null;
        if (s.equals("test")) {
            System.out.println("Match found");
        }
    }
}

Challenge : What's the bug and how do you fix it?

📋 Daily Micro-Project

Backend

Challenge :

Java RESTful API Endpoint with Spring Boot

• Create /greet/{name} that returns a greeting message.
• Use @RestController and @PathVariable.

Timebox: 30 minutes

Trivia: 5 Fun Facts

1. Java was originally called Oak.
2. Kotlin was officially released by JetBrains in 2011.
3. The first high-level programming language was Fortran.
4. CSS animations can be hardware-accelerated using transform.
5. Java's JVM allows it to run on any platform (“Write Once, Run Anywhere”).

Tool & Resource of the Day

Tool : JRebel

A Java productivity tool that allows code changes without restarting the server.

https://www.jrebel.com/

Resource Roundup ( Java/Kotlin ) :

• Kotlin Playground: play.kotlinlang.org
• Spring Boot Cheat Sheet: Spring.io Docs

Interview Question of the Day

Daily Interview Questions

Frontend :
1. What does position: absolute mean in CSS?
2. Explain how z-index works in layered elements.
3. What’s the difference between @keyframes and transitions?
4. What are pseudo-elements in CSS?

Backend ( Java/Kotlin ) :
1. Explain Java's Garbage Collection process.
2. What are the key differences between Java and Kotlin?
3. How does Spring Dependency Injection work?
4. How do coroutines in Kotlin differ from Java threads?

Database :
1. What is normalization and why is it important?
2. Difference between DELETE, TRUNCATE, and DROP.
3. What is a composite key in SQL?

Others :
1. What is the role of a hypervisor in virtualization?
2. Difference between Virtual Machine and Docker Container?

Daily Quiz Challenge

Frontend Quiz ( CSS ) :

1. What does animation-fill-mode: forwards; do?
2. Which unit is relative to the viewport height?
3. What’s the effect of transform: scale(1.5)?

Backend Quiz ( Java/Kotlin ) :

1. What is the default scope of a Spring bean?
2. What is the use of final keyword in Java?
3. Which Kotlin function starts a coroutine?
• startCoroutine()
• launch()
• begin()
• newCoroutine()

Others :

1. What is the purpose of GROUP BY in SQL?
2. Which port does HTTP use by default?

Mixed Quiz :

1. What will be the output of System.out.println(10 + 20 + "30"); in Java?

Weekly Cross-Domain Activities ( June 06 to June 12, 2025 )

API of the Day:

OpenWeatherMap API :

Challenge : Create a TypeScript + React component that fetches and displays current temperature and condition for a searched city.

Linux/DevOps Tip :

5 Handy Disk & Memory Commands

• df -h: disk usage
• du -sh *: directory sizes
• free -m: memory usage
• top: process monitoring
• vmstat: system performance

Real-World Project of the Week ( June 06 to June 12, 2025 )

Project of the Week:

Build a Job Listing Board with search, filter by tech stack, and posting forms. Stack: React + Node.js + PostgreSQL

Collaborative Project:

Contribute to dev.to open-source. It’s the engine behind dev.to—built with Ruby on Rails.

Case Study:

Notion Clone UI – Study how Notion handles blocks and dynamic layouts using React.

Instagram Stories Feature

• Built using horizontally swipable carousels
• Preloading, caching, and state transitions

Challenge: Recreate it using React + CSS Transitions.