是要统一开始时间吗，只能在凌晨1：00开始吗？

蒟蒻怕理解错，原文如下：

Note regarding the platinum contest: For USA students participating in the platinum-level contest, you will earn a certified score if you start the contest between 12:00 and 12:15 eastern time (ET) on Saturday, Dec 16. Certified scores carry more weight during finalist selection. This special timing currently only affects the platinum contest. That is, platinum problems become available only at noon ET on Dec 16, while all other divisions launch the morning of Dec 15. Students who wish to receive full consideration for selection as a finalist to attend our training camp should try to receive certified scores on all of the platinum contests. Realizing that schedules are sometimes hard to coordinate, students with three instead of four certified scores will still receive full consideration. Students who have fewer than three certified scores due to promotion from gold to platinum mid-season may also be considered for finalist status (in this case, the more certified scores, the better).