I applied through a recruiter. The process took 2 weeks.

The coding round itself isn't particularly difficult. The challenge isn't solving the problem—it's writing code that could realistically be shipped to production. Getting the code to work is the baseline. What the interview really evaluates is whether you naturally make production-quality engineering decisions:

• choosing appropriate data models
• validating inputs
• designing maintainable APIs
• handling edge cases
• considering concurrency
• writing tests
• producing code that can evolve as requirements change

My impression is that they're testing engineering habits more than pure problem-solving ability. You can solve the problem correctly and still struggle if your design choices suggest the code wouldn't be suitable for a real production system.

Build a regional bank for users to deposit money.