Daily Coding Challenges & Projects

Frontend Mini Project Challenge

Category : JavaScript Logical Puzzle + JavaScript Debugging

Challenge :

Write a function groupByLength(arr) that takes an array of strings and returns an object grouping strings by their length without using any built-in grouping methods.

Example :

groupByLength(["hi", "yes", "cat", "dog", "a"]);
// Expected Output:
// { '1': ['a'], '2': ['hi'], '3': ['yes', 'cat', 'dog'] }

Debugging Task :

function multiply(a, b) {
    return a * b;
}
console.log(multiply(5)); // What's wrong?
// Fix the bug so that missing arguments default to 1.

Backend Challenge

Category : C, C++, C#

Problem :

Write a C program to check if a linked list contains a cycle without using extra memory.

Example :

• Input : Linked list with a cycle → Output: "Cycle detected"
• Input : Linked list without a cycle → Output: "No cycle"

Database Query Challenge

Problems on SQL - HR Database :

1. Find employees who joined in the last 90 days
2. Find employees who have not received a salary increase in the last 2 years

Data Structures & Algorithms Challenge

• Easy:
• Problem :Reverse an array in place without using extra space.
• Hint :Use two pointers, swap from both ends.
• Medium:
• Problem : Implement a function to check if two strings are anagrams.
• Hint :Use character frequency count.
• Hard:
• Problem :Find the shortest path in a weighted graph using Dijkstra’s algorithm.
• Hint :Use a priority queue/min-heap.

Bug of the Day

Language : C

C Bug

Buggy Code:

#include <stdio.h>

int main() {
    int arr[5] = {1, 2, 3, 4, 5};
    for (int i = 0; i <= 5; i++) {
        printf("%d\n", arr[i]);
    }
    return 0;
}

Challenge : Find and fix the bug so it doesn’t print garbage values or cause segmentation fault.

📋 Daily Micro-Project

Type : Frontend

Task :

Create a glowing button with only HTML & CSS that changes color when hovered.

Trivia: 5 Fun Facts

1. JavaScript was created in just 10 days by Brendan Eich in 1995.
2. C language was developed by Dennis Ritchie in 1972 at Bell Labs.
3. The first-ever website is still online: info.cern.ch.
4. Python was named after the comedy show Monty Python’s Flying Circus, not the snake.
5. CSS3 introduced animations and transitions without JavaScript.

Tool & Resource of the Day

Tool : CodePen

Use : An online playground for front-end developers to write HTML, CSS, and JS code and see results instantly. Great for quick experiments.

Interview Question of the Day

Daily Interview Questions

Frontend :
1. What is the difference between null and undefined in JavaScript?
2. Explain event delegation in JavaScript.
3. How does the Virtual DOM in React improve performance?
4. What are Vue.js watchers used for?

Backend :
1. Difference between synchronous and asynchronous programming in Node.js?
2. What is a thread vs. a process?
3. How does Python manage memory?
4. REST API vs GraphQL differences?

Database :
1. Difference between INNER JOIN and LEFT JOIN?
2. How does indexing improve query performance?
3. SQL vs NoSQL differences?

Others :
1. What are system calls in OS? Example?
2. What is containerization, and how does Docker help in deployment?

Daily Quiz Challenge

Frontend :

1. What is the output?

console.log([] + []);

• []
• ""
• undefined
• null
2. Which CSS property is used for transitions?
• transform
• transition
• translate
• animate
3. What does document.querySelectorAll() return?
• Array
• HTMLCollection
• NodeList
• Object

Backend :

1. In C, which keyword allocates dynamic memory?
• malloc
• alloc
• memalloc
• new
2. In C++, what does RAII stand for?
• Resource Acquisition Is Initialization
• Random Access Input Initialization
• Recursive Allocation in Iterations
• Resource Allocation Is Immediate
3. Which C# keyword is used to define a constant?
• constant
• const
• readonly
• define

Mixed :

1. Database : Which SQL clause filters aggregated results?
2. Other : Which OS is the basis for Android?

Weekly Cross-Domain Activities ( August 01 to August 07, 2025 )

API of the Day:

Build a crypto tracker using the CoinGecko API.

Display current prices and 24h change of selected coins.

Linux/DevOps Tip :

Top 10 htop features for server monitoring (process tree, CPU graph, filter by user, etc.)

Real-World Project of the Week ( August 01 to August 07, 2025 )

Project of the Week:

Build a Task Manager App with React + Node.js + MongoDB (MERN Stack)

Collaborative Project:

Create an Open Source GitHub repo for “Interview Prep Hub” – collect user-submitted questions and answers.

Case Study:

Explore how Notion manages blocks and rich content – replicate a basic block-based note editor with contenteditable elements.