Daily Coding Challenges & Projects

Frontend Mini Project Challenge

Theme : CSS Animation Effects

Challenge :

Create a "bouncing dots loading indicator" using only CSS.

Requirements :

• Use @keyframes to animate.
• Create 3 dots bouncing in a loop.
• No JavaScript.

Bonus : Add delay so each dot animates in sequence.

Backend Challenge

Language Focus : Java, Kotlin

Challenge :

Java API Problem : Create a RESTful endpoint in Spring Boot that receives a POST request with a list of integers and returns their sum.

Bonus: Add input validation and return meaningful HTTP status codes.

Database Query Challenge

Problems on SQL - HR Database :

1. Write a SQL query to list employees who report to the same manager as ‘Steven King’.
2. Write a query to find departments that have more than 3 employees hired in the last 6 months.

Data Structures & Algorithms Challenge

• Easy:
• Problem : Given an array of numbers, find the second smallest number.
• Hint : Track two minimums while iterating.
• Medium:
• Problem : Implement an LRU Cache using a combination of HashMap and Doubly Linked List.
• Hint : Use get() and put() with O(1) time.
• Hard:
• Problem : Given a list of jobs with deadlines and profits, schedule to maximize profit assuming only one job can be done at a time.
• Hint : Greedy approach, sort by profit, track slots.

Bug of the Day

Language Focus :

Language : Java

Buggy Code:

public class Test {
  public static void main(String[] args) {
    int[] arr = null;
    if (arr.length == 0) {
      System.out.println("Empty array");
    }
  }
}

Find and fix the issue. :

Hint : What's the value of arr?

📋 Daily Micro-Project

Backend Focus :

Project :

Create a simple Java CLI tool to convert temperatures between Celsius and Fahrenheit.

• Use Scanner for input.
• Support both directions.
• Handle incorrect input gracefully.

Trivia: 5 Fun Facts

1. Kotlin was officially endorsed by Google for Android in 2017.
2. CSS was first proposed by Håkon Wium Lie in 1994.
3. Java was originally called Oak.
4. The term “bug” in computing dates back to a real moth found in a relay.
5. Kotlin's name comes from Kotlin Island near St. Petersburg, Russia.

Tool & Resource of the Day

Tool : Animista

Website to explore and copy-paste ready-made CSS animations

https://animista.net

Resource Roundup :

• CSS Animation Cheat Sheet - https://animate.style
• JavaScript: The Definitive Guide (MDN online)
• MDN CSS Transforms & Transitions Docs

Interview Question of the Day

Daily Interview Questions

Frontend :
1. How do transition and animation differ in CSS?
2. What is z-index and how does stacking context affect it?
3. How does position: sticky work?
4. Explain how reflow and repaint differ in browser rendering.

Backend :
1. What are checked vs unchecked exceptions in Java?
2. How does Kotlin handle null safety?
3. What are Java Streams? How do they support functional programming?
4. Explain the JVM memory model (heap, stack, metaspace).

Database ( SQL ) :
1. What does DISTINCT do in SQL?
2. What is the use of EXPLAIN PLAN?
3. How does GROUP BY differ from ORDER BY?

Others :
1. What is a race condition? How do you prevent it?
2. What is the difference between CI and CD?

Daily Quiz Challenge

Frontend Quiz :

1. What property is used to make elements fade in and out in CSS?
• opacity
• visibility
• display
• index
2. Which CSS unit is relative to the font-size of the root element?
• rem
• em
• vh
• px
3. Which of the following enables a CSS animation to loop infinitely?
• animation-delay: infinite
• animation-iteration-count: infinite
• animation-name: loop
• animation-duration: forever

Backend Quiz :

1. What is the output of System.out.println(10/0); in Java?
• 0
• Infinity
• Compilation error
• Runtime exception
2. In Kotlin, which keyword is used to define immutable variables?
• var
• const
• val
• final
3. Which collection in Java does not allow duplicate elements?
• List
• Map
• Set
• Array

Others :

1. Database : What does the HAVING clause filter?
• Rows
• Columns
• Groups
• Tables
2. General : Which file is used in Git to ignore files?
• .gitconfig
• .gitkeep
• .gitignore
• .ignore

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.