According to the above, I think 2 1 is an odd number, and it is necessary for one person to draw lots to decide the outcome of a game. If it is bye at 1 position, 2-3 4-5 6-7 8-910-12-. 14-1516-1718-19 20-21If this round wins 2, 5, 7, 8,/kloc. The negative team is 3-4 6-911-1214-19-21(whoever loses will be eliminated), and this round is 3, 6, 7. Negative continuation 3-6 1 1-17 191,elimination 3,11/9 This round continues to 65438. This time, 3, 1 1 wins, 1 and 19 are eliminated, followed by 3, 113 wins,1eliminated.
Next, the winners of the first round, No.2, No.5, No.7, No.8, 10, 13, 15, 16, 18, 20 and 3, will continue the competition. 2-5 7-8
10-1315-1618-20 continue to be eliminated by double defeat, and the winning team in the first round is the champion. The loser of the winning team who lost only one game in the first round competed with No.3 who lost only two games (two runners-up who lost only one game).
The above is my opinion for your reference ~