The second minute: the two players who got the news before the coach can inform the other two players, and then three players always get the news;

The third minute: The four players who got the news before the coach can inform the other four players. At this time, there are always seven players who get the news.

Minute 4: The eight players who got the news before the coach can inform the other eight players. At this time, 15 players got the message.

Minute 5: The coach's 16 player who got the news before can inform other 16 players. At this time, 3 1 players get the message. ……

So you can notify 20 players in 5 minutes at most.

In this way, at most 2 players with n- 1(2 to the nth power minus 1) can be notified within n minutes.

How's it going?