CF problemset to contest

Display CF problems in the contest field instead of problemset

这些是代码更新过的版本。 显示所有版本

  • v2.2 2020-11-06 Imported from URL
  • v2.1 2020-06-09 Imported from URL
  • v2.2 2020-06-09 run at document-start, suggested by @z4120
  • v2.1 2019-10-17 Imported from URL
  • v1.0 2019-10-14