Machine coding round: a simple question focusing on low-level design. For example, a parking system design with queries by vehicle number, parking location, etc.

This is followed by a data structure and algorithm round, or coding on paper.

Given stock prices for each day, find the best day to buy and sell (local minima, maxima problem).

I initially gave an O(n^2) solution, which I then corrected to an O(n) solution. I was rejected even though the solution was right. Overall, it was a bad interview experience. You don't expect to be rejected for not giving a right answer to begin with.