Daily Coding Challenges & Projects

Frontend Mini Project Challenge

Focus : CSS Animation Effects

Small Challenge 1 — CSS Animation Effect :

Challenge

Create a floating pulsing orb animation using only CSS.

Requirements :

• The orb should gently float up and down
• Glow effect using box-shadow
• Smooth infinite animation

Small Challenge 2 — CSS Debugging Challenge

Buggy CSS Code :

.box {
  width: 100px;
  height: 100px;
  background: red;
  animation: pulse 1s infinite;
}

@keyframes pulse {
  0% { transform: scale(1); }
  50% { transform: scale(1.2) }
  100% transform: scale(1);
}

Task :

Fix the animation so that it actually runs.

Hint : There’s a syntax issue.

Suggested Playgrounds :

• CodePen
• JSFiddle
• CodeSandbox

(Users can drop this animation code directly and see results.)

Backend Challenge

Focus : Java, Kotlin

Java Challenge :

Write a Java method to find the longest substring without repeating characters, returning both the substring and its length.

Kotlin Challenge :

Create a Kotlin function that:

• Reads a JSON file
• Converts it to a Kotlin data class list
• Filters items based on a condition
• Returns sorted output

(You must use coroutines for I/O.)

Database Query Challenge

Problems on SQL - HR Database :

1. List employees whose salary has not changed in the last 2 years, sorted by earliest hire date.
2. Find all employees with more than one manager change, showing employee ID + number of manager swaps.

Data Structures & Algorithms Challenge

• Easy:
• Problem : Return the count of elements greater than a given number X.
• Hint : Single pass → increment counter.
• Medium:
• Problem : Given a grid of 0s and 1s, count the number of islands (connected components).
• Hint : Use DFS or BFS; mark visited cells.
• Hard:
• Problem : Given an array with positive & negative numbers, find the maximum product subarray.
• Hint : Track both max and min products at each step.

Bug of the Day

Focus : Java, Kotlin

Buggy Code ( Java ) :

String s = null;
if (s.equals("hello")) {
    System.out.println("match");
}

Find the bug and fix the crash.

Buggy Code ( Kotlin ) :

val nums = listOf(1, 2, 3)
val doubled = nums.map { n -> n * 2 }
println(nums[3])

Why does this crash?

📋 Daily Micro-Project

Focus : Backend

Task :

Build a Basic Authentication Middleware (Java/Kotlin)

Requirements :

• Checks for Authorization header
• Validates username + password (hardcoded or config)
• Blocks request if credentials invalid
• Logs request time and method

Bonus : Support Base64 decoding of credentials.

Trivia: 5 Fun Facts

1. Kotlin was officially supported by Google for Android in 2017.
2. Java was originally meant for smart TVs before web use.
3. CSS animations became widely supported only after 2014.
4. The first CSS specification was published in 1996.
5. Oracle owns Java trademark but Kotlin is owned by JetBrains.

Tool & Resource of the Day

Tool : Postman

Essential for testing backend APIs.

Resource Roundup :

• Download "Modern Java Cheat Sheet" – covers streams, lambdas, collections, JVM internals.

Interview Question of the Day

Daily Interview Questions

Frontend :
1. What is the difference between transition and animation in CSS?
2. Explain how transform affects layout.
3. What is GPU acceleration in CSS animations?
4. What does will-change do?

Backend :
1. What is the JVM and how does it work?
2. Explain the difference between JDK, JRE, and JVM.
3. What are Kotlin coroutines and why are they better than threads?
4. Explain Java Garbage Collection.

Database :
1. What is the difference between WHERE and HAVING?
2. Explain what a surrogate key is.
3. What are materialized views?

Others :
1. What is a virtual machine?
2. Define concurrency vs parallelism.

Daily Quiz Challenge

Frontend CSS ) :

1. What does animation-fill-mode: forwards; do?
2. Which property triggers GPU acceleration: transform or top?
3. What unit is relative to the viewport height?

Backend ( Java / Kotlin ) :

1. What keyword prevents method overriding in Java?
2. What is the default visibility in Kotlin?
3. Does Java support multiple inheritance? Explain.

Database :

1. What does the SQL keyword DISTINCT do?

Other :

2. Which OSI layer does TCP operate on?

Mixed Quiz :

3. Which is faster:
• CSS transform: translate()

or

• Changing top & left?

Explain briefly.

Weekly Cross-Domain Activities ( November 22 to November 27, 2025 )

API of the Day:

Integrate the OpenWeatherMap API and build a small weather widget showing temperature, city, and weather icon.

Linux / DevOps Tip :

Use top, htop, and vmstat to monitor CPU, memory, and process usage live on Linux servers.

Real-World Project of the Week ( November 22 to November 27, 2025 )

Project of the Week:

Build a “Personal Finance Tracker” — Track expenses, visualize data with charts, and store in a backend DB.

Collaborative Project :

Contribute to an open-source Habit Tracker App on GitHub (Frontend: React, Backend: Node.js).

Case Study :

Study how Spotify’s recommendation system works — replicate a mini version using a dataset and cosine similarity.