DMOJ's rating system was based off of Topcoder's rating system, using rating and volatility to rank contestants. Topcoder's rating system has a flaw that contestants who wish to maximize their rating have incentives to underperform in contests to increase their volatility, as higher volatility leads to larger rating changes. For similar reasons to the above, contestants' ratings do not converge quickly to their true rating. Due to these flaws in the current rating system, DMOJ has moved to a new rating system called Elo-MMR.
Elo-MMR is a rating system designed by Aram Ebtekar and Paul Liu. It's designed to be used in formats where multiple contestants compete in rated competitions at the same time and can be ranked discretely against each other. It is designed to converge contestants' ratings more quickly than existing rating systems. Furthermore, contestants wishing to maximize their rating are never incentivized to underperform in any competition.
Because of the migration, user ratings have been retroactively changed as if DMOJ had always been using Elo-MMR. On average, users' ratings will have increased slightly, so rating cutoffs for titles have been increased accordingly. The new rating title boundaries look like this:
The rating distribution on DMOJ looks as follows:
For further technical details on exactly how Elo-MMR works, please refer to this paper.
From Saturday, July 31st to Wednesday, August 4th, we'll be hosting An Animal Contest 3. Participants will have a 3-hour window to complete 8 problems centered around monkeys! See the contest page for more details.
Note that unlike AAC2, AAC3 is rated for everyone.
July 17th is World Emoji Day. On most platforms, the calendar emoji 📅 shows this date. Naturally, to celebrate this day, we'll be hosting a week-long contest about calendars.
See the contest page for more details.
From Monday, June 21st to Monday, June 28th we'll be hosting the Bayview Secondary School 2021 Junior Programming Contest! This contest is a culmination of what Bayview Computer Club has learned over the past year. Unfortunately, the senior contest will be hosted at a later date. Participants will have a 3-hour window to complete 6 problems. See the contest page for more details.
From Saturday, May 22nd to Monday, May 24th we'll be hosting the first (and hopefully last) ever Quarantine Computing Contest! This contest features the very contagious COVID-19. Participants will have a 2.5-hour window to complete 7 problems. See the contest page for more details.