The following question was asked and not (yet) answered at [Math Stack Exchange][1]. > There are $n$ horses. At a time only $k$ horses can run in the single race. What is the minimum number of races required to find the top $m$ fastest horses? Please explain your answer. The $n = 25, k = m = 5$ case was a Google interview question and there are various answers on the web. But I am not sure what the right answer should be for this. Any ideas? [1]: https://math.stackexchange.com/questions/209790/how-to-find-a-total-order-with-constrained-comparisons