Coding question - Evaluate arithemetic expression like -1+2+3-4. Solved it with a bit of thinking. Interviewer found a bug and fixed it. The program ran correctly.

Other questions -

1. What is the difference between goroutine and os threads?
2. In databases how are indexes implemented? B+tree. And why are they used? Self balancing, low height hence fast operations.
3. Why don't we create indexes for all the columns in a table? Costly wrt money and writes would be costlier as data from main table needs to be propagated to all indexes (if strong consistency is needed).

Verdict: Reject.
Reason: Asked for feedback, no reason. Time waste.