splitter.py

from fastapi import FastAPI
from dataclasses import dataclass
from pydantic import BaseModel

class Txn(BaseModel):
    amount: int
    receiver: str
    sender: str

class TxnDto(BaseModel):
    txns: list[Txn]


api = FastAPI()

@api.post("/")
def add_txns(body:  TxnDto):
    return calculate(body.txns)



def calculate(txns: list[Txn]) -> list[Txn]:
    worth = {}

    for txn in txns:
        worth[txn.receiver] = 0
        worth[txn.sender] = 0


    for txn in txns:

        receiver = txn.receiver
        sender = txn.sender

        worth[receiver] += txn.amount
        worth[sender] -= txn.amount

    receivers = []
    senders = []

    for k, v in worth.items():
        if v < 0:
            receivers.append({"name": k, "amount": -v})
        else:
            senders.append({"name": k, "amount": v})


    receivers = sorted(receivers, key=lambda x: x['amount'], reverse=True)
    senders = sorted(senders, key=lambda x: x['amount'], reverse=True)

    print(receivers, senders)


    optimized_txns : list[Txn] = []

    while True:

        if len(senders) == 0:
            break

        if len(receivers) == 0:
            break

        chosen_sender = senders[0]
        chosen_receiver = receivers[0]


        if chosen_receiver['amount'] < chosen_sender['amount']:
            optimized_txns.append(Txn(amount=chosen_receiver['amount'], receiver=chosen_receiver['name'], sender=chosen_sender['name']))
            chosen_sender['amount'] -= chosen_receiver['amount']
            chosen_receiver['amount'] = 0 

        if chosen_receiver['amount'] > chosen_sender['amount']:
            optimized_txns.append(Txn(amount=chosen_sender['amount'], receiver=chosen_receiver['name'], sender=chosen_sender['name']))
            chosen_receiver['amount'] -= chosen_sender['amount']
            chosen_sender['amount'] = 0

        if chosen_receiver['amount'] == chosen_sender['amount']:
            optimized_txns.append(Txn(amount=chosen_sender['amount'], receiver=chosen_receiver['name'], sender=chosen_sender['name']))
            del senders[0]
            del receivers[0]
            continue

        if chosen_receiver['amount'] == 0:
            del receivers[0]

        if chosen_sender['amount'] == 0:
            del senders[0]

    return optimized_txns

@CaffeineDuck good job

@Neeraj319 where is frontend