The Stripe VO interview experience was great. The questions were all based on real-world payment and transaction scenarios, which really tested the ability to abstract and optimize practical problems. I was able to solve both questions smoothly, so I’d like to briefly share my approach.

Question 1: Minimum Transactions for Multi-Party Debt Settlement
The problem gives a set of borrowing and lending records among a group of people, and asks for the minimum number of transactions required to settle all balances so that everyone’s net balance becomes zero.

Core idea:
First, compute each person’s net balance and only keep those whose balance is non-zero. Then use a backtracking or greedy approach to match positive and negative balances as efficiently as possible. For example, if one person owes 50 and another is owed 50, a single transaction between them settles both accounts. By maximizing such direct cancellations, we can minimize the total number of transactions.

Follow-up:
If the debt relationships are very complex and involve hundreds of people, can your algorithm still maintain good efficiency?

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