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Vietnam Contests
Vietnam Team Selection Test
2020 Vietnam Team Selection Test
3
3
Part of
2020 Vietnam Team Selection Test
Problems
(1)
A football game
Source: 2020 Vietnam TST P3
6/29/2020
Suppose
n
n
n
is a positive integer,
4
n
4n
4
n
teams participate in a football tournament. In each round of the game, we will divide the
4
n
4n
4
n
teams into
2
n
2n
2
n
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
a
a
a
, 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.
Vietnam
TST
combinatorics