Code Challenge

Solutions for three coding challenges covering algorithms, frontend development, and code review.

Problems

Problem 1 — Sum to N

Three implementations of a function that computes the sum of integers from 1 to n:

Approach	Complexity	Description
sum_to_n_a	O(1)	Mathematical formula: n * (n + 1) / 2
sum_to_n_b	O(n)	Iterative loop
sum_to_n_c	O(n)	Recursion

Language: JavaScript

Problem 2 — Currency Swap Form

A modern token swap interface with real-time exchange rates, searchable token selector, and theme toggle.

Tech stack: React 19, TypeScript, Vite 5, Tailwind CSS v4

Key features:

• Token prices from Switcheo API
• Debounced search, input validation, swap direction toggle
• Dark/light theme (persisted in localStorage)
• Mobile responsive

See src/problem2/README.md for setup instructions.

Problem 3 — Messy React (Code Review)

A detailed code review identifying 13 issues in a poorly-written React component for displaying wallet balances. Includes the refactored solution with explanations.

Issues covered: undefined variables, inverted filter logic, missing interface properties, improper memoization, unstable React keys, unused variables, and more.

See src/problem3/readme.md for the full analysis.

Project Structure

src/
  problem1/
    sum_to_n.js           # Three sum implementations
  problem2/
    src/                  # React app source code
    package.json          # Dependencies and scripts
    README.md             # Setup and details
  problem3/
    readme.md             # Code review document