Daily Coding Challenges & Projects

Frontend Mini Project Challenge

Category : JavaScript Logical Puzzles, JavaScript Debugging

Challenge 1: JavaScript Logical Puzzle

Title : Flatten a Nested Array Without Recursion

Prompt :

Write a function flattenArray(arr) that flattens a deeply nested array without using recursion.

Example Input :

[1, [2, [3, 4], 5], 6]

Expected Output

[1, 2, 3, 4, 5, 6]

Hint : Consider using a stack or loop with Array.isArray().

Challenge 2: JavaScript Debugging

Buggy Code:

const nums = [1, 2, 3, 4];
const squared = nums.map(n => {
  n * n;
});
console.log(squared); // Why doesn't it return squares?

Challenge : Identify and fix the issue.

Backend Challenge

Language Focus : C, C++, C#

C Programming : Reverse a Linked List

Prompt : Write a function in C to reverse a singly linked list.

C++: Count Unique Characters in a String

Prompt : Write a function to return the count of distinct characters in a given string using STL.

C#: Fibonacci using Memoization

Prompt : Implement a function in C# to find the nth Fibonacci number using memoization.

Database Query Challenge

Problems on SQL - HR Database :

1. Find employees who joined in the last 3 months.
2. Find employees who haven't received a salary increment in the last 2 years.

Data Structures & Algorithms Challenge

• Easy:
• Problem :Find the Maximum Element in an Array
• Hint :Loop once through the array.
• Medium:
• Problem : Two Sum Problem
• Hint :Use a hashmap to store complements.
• Hard:
• Problem :Implement an LRU (Least Recently Used) Cache
• Hint :Use HashMap + Doubly Linked List.

Bug of the Day

Language Focus : C

C Bug

Buggy Code:

#include
int main() {
   int a = 10;
   if(a = 5) {
       printf("True\n");
   } else {
       printf("False\n");
   }
   return 0;
}

Challenge : Find and fix the logical bug in the condition.

📋 Daily Micro-Project

Frontend :

Task :

Project : Build a Glowing Button

• Description : Create a glowing effect using only CSS.
• Hint : Use box-shadow and transition.

Trivia: 5 Fun Facts

1. Who created JavaScript?
2. What was the first programming language?
3. What year was Python released?
4. Who developed C++?
5. Which company created the TypeScript language?

Tool & Resource of the Day

Tool : JSFiddle

Use : Online playground for JS/CSS/HTML

Link : https://jsfiddle.net

Resource Roundup :

• 30 Seconds of Code (JS Snippets)
• CSS Tricks
• Free JavaScript eBook

Interview Question of the Day

Daily Interview Questions

Frontend :
1. What is the difference between null and undefined in JS?
2. How does event delegation work?
3. Explain the Virtual DOM in React.
4. Difference between computed and watch in Vue.js?

Backend :
1. Difference between synchronous and asynchronous programming in Node.js?
2. Difference between thread and process?
3. How does memory management work in Python?
4. RESTful API vs GraphQL?

Database :
1. Inner Join vs Left Join
2. How does indexing work?
3. SQL vs NoSQL?

Others :
1. What are system calls in OS? Example?
2. What is containerization? How Docker helps?

Daily Quiz Challenge

Frontend :

1. What will this return: typeof NaN?
• number
• NaN
• undefined
• object
2. Which CSS property makes an element semi-transparent?
• opacity
• transparency
• blur
• alpha
3. React component lifecycle: What runs after the first render?
• componentDidMount
• render
• componentWillMount
• useMemo

Backend :

1. What is the output of 2 + "2" in JS?
• "22"
• 4
• Error
• NaN
2. Which keyword is used to define a coroutine in Python?
• async
• co
• yield
• def
3. In C++, which of the following creates a class?
• class
• def
• struct
• create

Others :

1. Which SQL clause is used to filter grouped rows?
• HAVING
• WHERE
• GROUP BY
• ORDER BY
2. Which container tool is best known for deployment?
• Docker
• Git
• Ansible
• Bash

Weekly Cross-Domain Activities ( July 25 to July 31, 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 ( July 25 to July 31, 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.