[FE] Nguyen Hoang Hieu | nguyenhoanghieu0312@gmail.com

[hieunh0312]

Summary

This PR completes all 3 problems in the 99Tech code challenge.

What Changed

Problem 1

• Implemented 3 versions of sum_to_n:
  • array + reduce
  • arithmetic formula n * (n + 1) / 2
  • iterative loop accumulation

Problem 2

• Rebuilt the currency swap UI using Vite + React + TypeScript
• Added live price fetching and normalization from the provided price feed
• Added token icon fetching
• Implemented two-way quote calculation:
  • editing pay recalculates receive
  • editing receive recalculates pay
• Added input validation, debounce, loading skeletons, retry state, and responsive layout
• Structured the code into reusable modules for API access, quote logic, and UI components

Problem 3

• Reviewed the provided refactor and documented findings in detected-issues.md
• Highlighted the major fixes in the refactored version, including:
  • runtime crash fix
  • corrected filtering logic
  • improved typing
  • deterministic sorting
  • safer rendering behavior
• Noted a few smaller remaining concerns and follow-up suggestions

Deployment

• Problem 2 demo: https://code-challenge-r71y.vercel.app/