MathDB
2018 General #9

Source:

November 12, 2018
probabilityexpected value

Problem Statement

2020 players are playing in a Super Mario Smash Bros. Melee tournament. They are ranked 1āˆ’201-20, and player nn will always beat player mm if n<mn<m. Out of all possible tournaments where each player plays 1818 distinct other players exactly once, one is chosen uniformly at random. Find the expected number of pairs of players that win the same number of games.