Split a check

split_check.py

import sys

def split_check(*args):
    """
    split_check(('josh', 50), ('jake', 100), ('isac', 100))
    """
    total = 0
    for name, amount in args:
        total += amount

    avg = total / len(args)

    print(f"Average: {round(avg, 2)}")

    recipients = {}
    payers = {}

    # Split into who overpaid and who underpaid
    for name, amount in args:
        diff = amount - avg
        if diff > 0:
            recipients[name] = {
                'diff': diff,
                'payments': 0
            }
        else:
            payers[name] = diff

    # Calculate total amount owed to all recipients
    total_recipients_owed = 0
    for name, adjustment in recipients.items():
        total_recipients_owed += adjustment['diff']

    # Calaculate the percentage of total due to each recipient
    for name, adjustment in recipients.items():
        percentage = adjustment['diff'] / total_recipients_owed
        recipients[name]['percentage'] = percentage

    # For each payer, pay the percentage of the amount owed to reach the average, to each recipient
    output = []
    for name, amount in payers.items():
        for receipient_name, adjustment in recipients.items():
            payment = amount * adjustment['percentage'] * -1
            recipients[receipient_name]['payments'] += payment
            if payment != 0:
                output.append(f"{name} pays {receipient_name} {round(payment, 2)}")

    # Check the math!
    for receipient_name, adjustment in recipients.items():
        if round(adjustment['diff'], 2) != round(adjustment['payments'], 2):
            print(f"Adjustment error!  Not all totals add up. {adjustment}")
            print(recipients)
            sys.exit(1)

    for line in output:
        print(line)