Expense splitter for a group trip

Add people and expenses, then see who owes whom with the fewest payments.

Why build it

The settle-up algorithm is a real problem with a clean solution, and money maths teaches you why floats are a trap.

Features

• Add people and shared expenses
• Equal or custom split per expense
• Running balance per person
• Minimal settle-up suggestions
• Export a summary as text

Roadmap

1. p1

   Model money safely

   • Store amounts as integer cents
   • Write split functions for equal and custom shares
   • Handle remainders so totals always add up
2. p2

   Balances

   • Compute net balance per person
   • Test with 3 to 6 people and uneven splits
3. p3

   Settle-up

   • Greedy match of biggest debtor to biggest creditor
   • Show the resulting payment list
   • Verify total paid equals total owed
4. p4

   UI and ship

   • Expense form with validation
   • Copy-to-clipboard summary
   • Deploy and document the algorithm in the README

Common pitfalls

• Using floating-point dollars, which leaves 1-cent errors
• Forgetting to distribute the remainder cent when splitting evenly

Skills you will practise

• Integer money handling
• Greedy algorithms
• Form validation