Ramiro N. Cosa

We solved "Second Best" from FreeCodeCamp, a challenge that involves finding the second most expensive laptop within a given budget, ignoring duplicate prices.

We Solve "Unorder Of Operations" from freeCodeCamp Daily Coding Challenge for August. We analyze the problem, develop a JavaScript solution, and discuss its complexity.

We solve "Most Frequent" from FreeCodeCamp, explore alternatives, and analyze its complexity.

We solve "Pounds to Kilograms" from the FreeCodeCamp Daily Challenge, explaining the analysis, development, and complexity of the solution.

We solve the FreeCodeCamp daily challenge "String Compression", explore alternatives, and analyze its complexity.

Today we solve "Date Formatter", a classic string and date manipulation challenge.

How to find exclusive elements between two arrays using Sets in JavaScript. O(n+m) complexity analysis and applied set theory.

We solve "Count Partitions with Even Sum Difference" from LeetCode Daily Challenge using TypeScript.

Solving the "Rotate Image" problem from LeetCode (Top Interview 150). We explain the transpose and reverse approach.

We solve the "Permutation Count" problem from FreeCodeCamp Daily Challenge. We explain the mathematical formula and present an efficient solution in JavaScript.

In today’s challenge, we tackle converting a Markdown ordered list item to its equivalent HTML format. The task is to validate the input string’s format and return the requested result or an error message as appropriate. To solve it, we fir...

We validate a 9x9 Sudoku board in a single pass, explaining the key formula and useful patterns for interviews.

Solving the FreeCodeCamp daily challenge: 'Camel To Snake'. It sounds like a circus act, but it's a string manipulation problem.

Solving the miles to kilometers conversion challenge, analyzing the process and presenting an optimal JavaScript solution.

Solving the "AI Detector" daily challenge: detecting AI-generated text using specific string analysis rules.

Have you ever wondered how classic video games like Pong calculate the movement of a ball? Today's FreeCodeCamp challenge invites us to simulate that behavior in a matrix using JavaScript. Given a matrix (array of arrays) indicating the cur...

Solving the FreeCodeCamp daily challenge "Reverse Parentheses" to invert content inside parentheses in JavaScript.

Solving FreeCodeCamp daily challenge for converting strings to camel case in JavaScript.

Greedy approach to solve the Jump Game problem from LeetCode.

Step-by-step explanation of LeetCode #3381: 'Maximum Subarray Sum with Length Divisible by K'.

Solving 'What's My Age Again?' from FreeCodeCamp Daily Challenge using JavaScript.

Solving the LeetCode Top-Interview problem "Best Time to Buy and Sell Stock II" using a profit-summing approach.

Today's problem is a variant of the classic "FizzBuzz"challenge, which happened to be yesterday's daily problem. In this new task, we must check if a given array strictly follows the FizzBuzz rules from 1 up to the last element. Given an ar...

Today we tackle LeetCode #121: Best Time to Buy and Sell Stock. This is the seventh challenge in the LeetCode Top Interview 150 set. You are given an array prices where prices[i] represents the price of a stock on day i. Your goal is to max...

FizzBuzz is one of the most popular problems in technical interviews and programming challenges. Although it seems simple, it's perfect for practicing logic, conditionals, and array manipulation. Given an integer $n$, return an array with t...

Efficient algorithm to check divisibility by five for binary prefixes.

We solve the "Message Validator" problem from FreeCodeCamp using regular expressions in JavaScript.

We solve the "Character Count" problem from FreeCodeCamp using arrays and string manipulation in JavaScript.

We solve the "Recipe Scale" problem from FreeCodeCamp by applying string manipulation and data structures in JavaScript.

We solve the Least Common Multiple (LCM) problem using the relationship between GCD and LCM in JavaScript.

We solve the LeetCode 'Rotate Array' problem with three different approaches, including an optimized one with O(n) time and O(1) extra space.

We solve the "Majority Element" problem from LeetCode (#169) using TypeScript. We explore an efficient solution with $O(n)$ time and $O(1)$ space complexity, applying the Boyer-Moore Voting algorithm.

Solving the "Longest Word" problem from FreeCodeCamp Daily Challenge using JavaScript.

We solve the fourth problem in LeetCode's Top Interview 150 series: Remove Duplicates from Sorted Array II. We explore an efficient solution.

Solving the "Markdown Heading Converter" challenge from FreeCodeCamp, converting Markdown headings to HTML.

In this post I share the process of migrating the app to Next.js, the challenges faced, and the solutions implemented.

We solve the "100 Characters" problem from FreeCodeCamp Daily Challenge with a detailed explanation.

How to design a mobile-first, accessible, and scalable UI using TailwindCSS v4, reusable components, and visual testing with Storybook.

We solve the FreeCodeCamp daily challenge "fingerprint-test".

Simple, clear explanation to count axis-aligned integer rectangles inside a w×h rectangle, with math notation and Mermaid diagrams.

Didactic explanation of the in-place Remove Element solution (LeetCode 27) using Two Pointers, with examples, tests and visualizations.

We solve the Greatest Common Divisor (GCD) problem using Euclid's Algorithm in JavaScript.

Solution analysis for the Days Until Weekend problem, with calendar visualization, step-by-step explanation and efficient date handling in JS.

Explained solution to the problem of shifting an array N positions using modular normalization and tests. Strategies, edge cases, and visualization.

How to connect validation, persistence, and the visual form using React Hook Form. Test examples and an outlook towards styling as a next step.

We solve the FreeCodeCamp daily challenge: "Email Signature Generator". We explain the approach, complexity, and provide a TypeScript solution.

We solve the first problem from the LeetCode Top Interview 150 Study Plan series: "Merge Sorted Array". We explain the approach, complexity, and provide a TypeScript solution.

Solving the FreeCodeCamp daily challenge: Vowels and Consonants. Step-by-step analysis and explanation of the solution.

How to save and retrieve validated records in localStorage, handling errors and tolerating corrupt data. Includes commented code, diagrams, and practical tests.

Solving FreeCodeCamp's daily challenge: Extract the extension from a filename.

How to implement robust data validation with Zod, leverage type inference in TypeScript, and write practical unit tests for your React model.

Solving the LeetCode problem: Count Operations to Obtain Zero.

Implementation of an algorithm to search for words in a 2D matrix, exploring in the four main directions.

Solving the Compare Version Number problem from LeetCode. Step-by-step analysis, multiple solutions and JavaScript optimizations.

Solving the character limit problem from November 7th FreeCodeCamp challenge. Step-by-step analysis with flow diagram.

Solving the LeetCode problem "Smallest Number With All Set Bits" (#3360). Analysis, strategy and TypeScript solution.

Solution to FreeCodeCamp daily challenge: Counting Cards. Step-by-step explanation and strategy analysis.

Full analysis of FreeCodeCamp Weekly Finder challenge: how to get the weekday from an ISO date string while avoiding timezone pitfalls, plus alternative approaches.

Practical guide to setting up Vitest, Testing Library, and automating testing in React + Vite. Includes diagrams, best practices, explanations for beginners, and troubleshooting.

An improved guide to designing the core data model for a nutritional tracker in React: practical decisions, visual diagrams, and scalable architecture.

Solution to the FreeCodeCamp daily challenge: building matrices with Array.from(). Comparison of approaches and analysis of when to use each one.

Solution to the FreeCodeCamp daily challenge: implement an image search function that filters file names by search term, ignoring case.

Solving the Power of Two problem from LeetCode. Step-by-step analysis, multiple solutions and JavaScript optimizations.