Daily Coding Challenges & Projects

Frontend Mini Project Challenge

Theme : CSS Animation Effect Challenge:

Example :

Create a button with the following animation:

• When hovered, the button background color transitions smoothly from blue to green over 0.5 seconds
• The button should also slightly scale up on hover.

Bonus : Make the text color change to white during the hover animation.

Backend Challenge

Java, Kotlin

Java Problem :

Write a Java method that finds the second largest number in an integer array.

Example:
 
int[] arr = { 4, 1, 7, 3, 9, 2 };  
// Output: 7  

Database Query Challenge

Problems on SQL - HR Database :

1. Write a SQL query to display employees who joined in the last 90 days.
2. Write a SQL query to find the names of departments that do not have any employees assigned.

Data Structures & Algorithms Challenge

• Easy:
• Problem :Given an array of integers, return the sum of all even numbers.
• Hint : Use modulus operator %.
• Medium:
• Problem : Check if two strings are anagrams (case insensitive, ignore spaces).

Example: "Listen" and "Silent" → true

• Hint : Sort and compare or use frequency maps.
• Hard:
• Problem :Find the Kth largest element in an unsorted array.

Example:  arr = [3, 2, 1, 5, 6, 4], k = 2 → 5 

• Hint :You can use a min-heap or quickselect algorithm.

Bug of the Day

Language Focus :

Language : Java

Buggy Code:

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

Challenge :

Find and fix the bug.

📋 Daily Micro-Project

Backend Focus :

Task :

Create a simple Java REST API endpoint using Spring Boot that returns the current server time in JSON format.

Trivia: 5 Fun Facts

1. Kotlin is officially supported by Google for Android development.
2. Java was originally developed by James Gosling at Sun Microsystems.
3. CSS was proposed by Håkon Wium Lie in 1994.
4. Java’s slogan was "Write Once, Run Anywhere".
5. The first version of SQL was developed by IBM in the 1970s.

Tool & Resource of the Day

Tool : Postman

Why : Essential tool for testing APIs, supports REST, GraphQL, and more.

Resource Roundup :

• Postman Learning Center
• Postman for Beginners YouTube Series
• API Collections: Download ready-to-use public APIs for testing

Interview Question of the Day

Daily Interview Questions

Frontend ( CSS / Animations Focus ) :
1. What is the difference between em and rem units in CSS?
2. How do CSS transitions differ from CSS animations?
3. What are keyframes in CSS animations?
4. How can you center an element vertically and horizontally with Flexbox?

Backend ( Java, Kotlin ) :
1. What is the difference between an interface and an abstract class in Java?
2. How does garbage collection work in the JVM?
3. What is the purpose of the final keyword in Java?
4. Explain how Kotlin handles null safety.

Database ( SQL ) :
1. What is a primary key constraint in SQL?
2. What is the difference between GROUP BY and ORDER BY?
3. Explain the ACID properties of a database transaction.

Others :
1. What is multithreading and why is it useful?
2. How does container orchestration with Kubernetes work?

Daily Quiz Challenge

Frontend Quiz ( CSS Focus ) :

1. What is the correct syntax for adding a transition effect?
• transition: all 0.5s;
• animate: all 0.5s;
• effect: all 0.5s;
• change: all 0.5s;
2. Which CSS property is used to create animations?
• @motion
• @keyframes
• @animation
• @effect
3. How do you scale an element to 1.2 times its size on hover?

:hover { transform: _________; } 

• scale(1.2)
• zoom(1.2)
• resize(1.2)
• enlarge(1.2)

Backend Quiz ( Java, Kotlin ) :

1. Which keyword is used to inherit a class in Java?
• inherit
• extends
• implements
• super
2. Kotlin's default for variables is:
• Mutable
• Immutable
• Null by default
• Optional
3. Which of the following is not a Java primitive type?
• int
• boolean
• float
• String

Database :

1. Which SQL statement is used to extract data from a database?
• SELECT
• GET
• FETCH
• EXTRACT

Mixed Quiz :

1. What is the output of:

console.log(typeof undefined === typeof null); 

• true
• false
• error
• undefined

Weekly Cross-Domain Activities ( June 27 to July 03, 2025 )

API of the Day:

Task : Build a real-time currency converter using the ExchangeRate API

https://www.exchangerate-api.com/

Linux/DevOps Tip :

Title : Top 5 Log Monitoring Commands: tail, grep, less, journalctl, watch

Real-World Project of the Week ( June 27 to July 03, 2025 )

Project of the Week:

Build a Book Management System with Vue.js + Node.js + PostgreSQL

Collaborative Project:

Contribute to an open-source to-do app with multi-user auth on GitHub.

Case Study:

Explore how Notion uses dynamic blocks and replicate a basic block editor.