Interview prep series: real problems, real trade-offs, no hand-waving.
The Problem Worth Solving
Here's a scenario straight from a fintech startup I worked at.
We had field agents responsible for onboarding customers, managing investments, and handling deposits and withdrawals. Management wanted to shift from a fixed salary model to fixed + commission — where commission depended on each agent's monthly performance.
The immediate instinct was: just write a SQL query. And that's exactly what we did, initially. But it quickly fell apart:
