    Sentence 1: If a building has ‘n’ floors and_‘m’  selections are currently active in the building's  elevator, what is the probability that the elevator  is currently at the (numerically least highlighted  number-1)th floor?    Sentence 2: There are n numbers in any random  order. How do  I get top m numbers (m <= n) in descending order  with least time complexity and most optimized?  (Java code)