dmoj.ca is now available over HTTPS to protect your privacy and identity. We value your security greatly, and have gone to all lengths to ensure that your password is safe and your session remain unhijacked. You can now safely browse dmoj.ca at an Internet café or an insecure school network without any fears of being eavesdropped on or impersonated. As an added bonus, pages should now load faster on browsers that support the SPDY protocol — in other words, all modern browsers.

View the Qualys SSL Labs report for DMOJ.

On a related note, dmoj.ca now delivers its assets over the domain https://dmoj.ml/. This is done for performance reasons, mainly to save cookie overhead and better exploit caching. Along with the move of static content to dmoj.ml, we've also seen fit to drop the www. prefix of dmoj.ca — www.dmoj.ca now redirects to dmoj.ca (this is why all your visited links are blue again).

We'll continue to optimize and enhance the usability of the DMOJ in the coming month. Progress is publicly tracked on GitHub, where you can also find what changes are in store for April.

Update 2: The correct date is actually April 2, 2015.

Update: The contest has been postponed to April 3, 2015.

The springtime of your adolescence is here! On Thursday, April the 2nd, take part in the 2nd GFSSOC, which will feature separate contests for the junior and senior level. Anyone with a DMOJ account is welcome to participate, and anyone without an account is welcome to register and participate.

The theme of this contest will be past GFSS computer science club head Calvin Liu, who is not with us anymore. RIP Calvin (2010 - 2014)

A reminder for anyone stuck on past GFSSOC questions to visit our organization page, where there is useful information. Detailed solutions for this contest will also be posted here the day after it is over.

Contest ratings similar to TopCoder's rating system have recently been implemented on the DMOJ. Rating is a direct indicator of how likely you are to beat someone else in any given contest. The higher your rating is compared to another person, the more likely you'll place better! There are currently six ranks, based on the numerical value of the rating.

The default rating for users is 1200.

Rating is calculated using your rank on all rated contests you participated in, while also taking into account your competitors.

To view your rating, go to https://dmoj.ca/user/HANDLE/. For example, to view quantum's rating, go to https://dmoj.ca/user/quantum/.

The ratings displayed on a post-contest scoreboard is the new rating of the user after they participated in the contest.

Note that the contents of this blog post are outdated. Refer to this blog for the current system and cutoffs.

Update: Contest is over! Ratings are updated, thanks for participating!

[Contest Announcement]

What: Three hard data structures problems!

When: Until March 23, 2015 midnight EDT.

Where: https://dmoj.ca/contest/mmcc15

In preparation for the 2015 CCO, bruce has put together a set of problems for all to practice for the CCO.

The contest consists of 3 challenging algorithmic problems roughly similar in difficulty to the Canadian Computing Olympiad.

The format is a virtual contest with 4 hours to solve 3 problems. The duration of the entire contest will be 4 days.

https://dmoj.ca/contest/ccoprep2

Enjoy!

Update: the maintenance period is over.

On March 3, 2015 at 4:00 UTC, our hosting provider will be performing maintenance on our servers to correct a security issue. A downtime of less than two hours is promised by the host. We apologize in advance for the inconvenience this may cause.

In preparation for the 2015 CCO, bruce has put together a set of problems for all to practice for the CCO.

The contest consists of 3 challenging algorithmic problems roughly similar in difficulty to the Canadian Computing Olympiad.

The format is a virtual contest with 4 hours to solve 3 problems. The duration of the entire contest will be 4 days.

Important: You will be able to access the problems from the main judge. This is intentional, to allow students to keep solving the problems after their 4 hour timer is up. However, if it's your first time doing this contest, please access it from the contest page to keep things fair for everyone. Thank you!

https://dmoj.ca/contest/ccoprep1

Enjoy!

All of CCO 2013 problems have been added.

https://dmoj.ca/problems/?category=24

Thanks to JeffreyZ for typing up all the statements!

Update: All solutions for 2015 are complete.

We are in the process of making detailed, high quality editorials for 2015 CCC (we may add past contests too at a later time). You can find them in Problems -> problem statement -> Read editorial.

• J1 - Special Day
• J2 - Happy or Sad
• J3 - Rövarspråket
• J4 - Wait Time
• J5 - π-day
• S1 - Zero That Out
• S2 - Jerseys
• S3 - Gates
• S4 - Convex Hull
• S5 - Greedy For Pies

...and more to come!

If you see mistakes in the editorials, or feel that they aren't detailed enough, open a ticket on the problem and we'll improve them. You can also do that if you want to contribute editorials for any year.