Sesame AI·Machine Learning Engineer·Technical Phone Screen
Jun 2026
Sesame AI asked me to implement a ring buffer from scratch, which sounds like a straightforward systems question until you're actually in the middle of it trying to remember which pointer tracks what. Solid technical screen, nothing behavioral, just code and follow-ups.
- Implement a circular buffer with a fixed byte capacity. It should support writing bytes (returning how many were written), reading up to N bytes from the front, and reporting how many bytes are currently available. Use head, tail, and size pointers with modulo arithmetic for wraparound, handle edge cases like a full buffer and reading past what's available, and briefly discuss thread safety.
“I got the basic structure down pretty quickly, head/tail/size, modulo on writes and reads.”