modify

app/controllers/competition_teams_controller.rb

@@ -49,7 +49,7 @@ class CompetitionTeamsController < ApplicationController
                 .having('total != 0 and finish >= (total / 2)').to_sql
     course_ids = Course.where('courses.created_at > ?', Time.parse('2018-06-01'))
                    .where('courses.created_at <= ?', @competition.end_time)
-                   .where("(#{student_count_subquery}) >= 10")
+                   .where("(#{student_count_subquery}) >= 3")
                    .where("exists(select 1 from homework_commons hcs where hcs.course_id = courses.id and hcs.publish_time is not null and hcs.publish_time < NOW() and hcs.homework_type = 4 and exists(#{subquery}))")
                    .joins('join course_members on course_members.course_id = courses.id and course_members.role in (1,2,3)')
                    .where(course_members: { user_id: @team_user_ids }).pluck(:id)