A football game
Source: 2020 Vietnam TST P3
June 29, 2020
VietnamTSTcombinatorics
Problem Statement
Suppose is a positive integer, teams participate in a football tournament. In each round of the game, we will divide the teams into pairs, and each pairs play the game at the same time. After the tournament, it is known that every two teams have played at most one game. Find the smallest positive integer , so that we can arrange a schedule satisfying the above conditions, and if we take one more round, there is always a pair of teams who have played in the game.