How to arrange the badminton match 18 people?

1。 Integral system, round robin, take the first 4 points, 4 into 2, 2 into 1 (more troublesome)

2。 Four people draw lots to play the game first, eliminate two, and then 16 enters 8, 8 enters 4, 4 enters 2, 2 enters 1.

3。 18 eliminated 9 people, 2 out of 9 people were eliminated in the lottery 1, and then 8,8 into 4,4 into 2,2 into 1 remained.

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