Compute Balances and Minimize Settlements
Daily Ledger Service: Balance Computation and Minimum Settlements
You are tasked with developing core components for a daily ledger service. This service processes financial transactions and facilitates settlements between users.
Part 1: Compute End-of-Day Balances
Given a list of transaction records for a single day, compute the net end-of-day balance for each user. Each transaction record contains:
timestamp: The time of the transaction.user_id: The identifier for the user involved.delta_amount: An integer representing the change in the user's balance. This can be positive (money received) or negative (money paid).
Assumptions for Part 1:
- All users start the day with a balance of 0.
- All
delta_amountvalues are integers.
Part 2: Generate Minimum Settlement Plan
Using the end-of-day balances computed in Part 1, generate a settlement plan. The goal of this plan is to ensure every user's final balance becomes 0, using the minimum possible number of individual transfers.
Settlement Transfer Format:
Each transfer should be represented as a tuple: (from_user, to_user, amount).
- A user with a negative balance must pay money.
- A user with a positive balance must receive money.
Constraints and Notes for Part 2:
- Users whose end-of-day balance is 0 do not need to be included in the settlement plan.
- You may assume that the sum of all users' end-of-day balances is exactly 0. This implies that the total money to be paid equals the total money to be received.
- For the exact-minimum settlement part, assume the number of users with non-zero balances is small enough to permit an exponential-search solution if necessary.
AI interview prep
Core dilemma
Optimizing multi-party debt settlement to achieve the absolute minimum number of transfers, given an initial balance state.
3 tradeoffs and 3 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
Compute Balances and Minimize Settlements
Daily Ledger Service: Balance Computation and Minimum Settlements
You are tasked with developing core components for a daily ledger service. This service processes financial transactions and facilitates settlements between users.
Part 1: Compute End-of-Day Balances
Given a list of transaction records for a single day, compute the net end-of-day balance for each user. Each transaction record contains:
timestamp: The time of the transaction.user_id: The identifier for the user involved.delta_amount: An integer representing the change in the user's balance. This can be positive (money received) or negative (money paid).
Assumptions for Part 1:
- All users start the day with a balance of 0.
- All
delta_amountvalues are integers.
Part 2: Generate Minimum Settlement Plan
Using the end-of-day balances computed in Part 1, generate a settlement plan. The goal of this plan is to ensure every user's final balance becomes 0, using the minimum possible number of individual transfers.
Settlement Transfer Format:
Each transfer should be represented as a tuple: (from_user, to_user, amount).
- A user with a negative balance must pay money.
- A user with a positive balance must receive money.
Constraints and Notes for Part 2:
- Users whose end-of-day balance is 0 do not need to be included in the settlement plan.
- You may assume that the sum of all users' end-of-day balances is exactly 0. This implies that the total money to be paid equals the total money to be received.
- For the exact-minimum settlement part, assume the number of users with non-zero balances is small enough to permit an exponential-search solution if necessary.