Friend Money Transfer / Payment System OOP

Problem Overview

You are given a list of API call strings, each prefixed with a sequential request_id. There are 5–6 request types: 1. REGISTER (user_id, initial_balance) — sign up a new user with an initial balance 2. FRIEND_REQUEST (user1, user2) — user1 sends a friend request to user2; the request is tracked…

• 3 candidate-reported follow-ups — the exact probes interviewers asked, with the trigger for each
• The rest of the problem statement — full requirements, constraints, and edge cases
• Approach and trade-offs — what passing candidates did, and the mistakes that sink people