The CCC is rapidly approaching, and so it's time for this year's Richmond Green Programming Contest to help you prepare!

The RGPC '18 will be a 3-hour virtual contest, which will allow contestants to participate in any 3-hour window from 12:00 AM EST, February 10, 2018 to 12:00 AM EST, February 12, 2018. Please see the contest page for more details.

Good luck on both the RGPC and the CCC!

We're excited to invite you to participate in a series of contests that will emulate the Canadian Computing Competition! These contests are being produced by ksun48, rpeng, xiaowuc1, and y0105w49 with the intended audience being any student who wishes to practice for the CCC.

All of these contests will be similar in format to the CCC — there will be a junior division and senior division with problems spanning the difficulty of the CCC. All of these contests are unrated.

The first contest will go live on January 29th, 2018 and be open for 72 hours. As with the regular CCC, the contest will be a 3-hour virtual contest which will allow contestants to participate in any 3-hour window for those three days.

We will be producing a set of five such contests from now until CCC. We wish everyone writing the CCC good luck on our contests and on the CCC!

Thanks for participating in the TLE '17 January contest!

The winners are:

1. y0105w49 (perfect score)
2. ksun48
3. ecnerwal
4. xiaowuc1
5. tmwilliamlin168

Editorials for each of the problems will be uploaded to the respective problem pages.

We hope you enjoyed the contest, and see you next month!

We're excited to invite you to the fifth Thorndeau Logic Evaluation of the 2017-18 school year!

The problem writers/testers of this round are rpeng, kobortor, ZQFMGB12, and d.

Note that this will be the last TLE before the Canadian Computing Competition, so give it your all!

The TLE '17 January contest will be a 3-hour virtual contest, which will allow contestants to participate in any 3-hour window from 12:00 PM EST, January 26, 2018 to 12:00 PM EST, January 27, 2018. Please see the contest page for more details.

See you soon!

Thanks to everyone who participated in the New Year's Contest! We hope that you enjoyed the contest! Congratulations to the winners:

1. xyz111 (perfect score)
2. jerrym
3. radoslav11
4. y0105w49
5. pmnox
6. REEmark
7. fanache99
8. azneye
9. ksun48
10. Rafbill

Editorials have been uploaded to their respective problem pages.

Happy New Year!

We hope everyone's been enjoying their winter break because it's about to get better!

On January 1, we will be hosting DMOJ's own New Year's 2018 contest. Please see the contest page for details.

Anyone with a DMOJ account is welcome to participate, and anyone without one is welcome to register and participate.

See you soon, good luck, and Happy Holidays from all of the DMOJ crew!

Thanks for participating in the TLE '17 December contest!

The winners are:

1. y0105w49 (perfect score)
2. rpeng (perfect score)
3. xyz2606 (perfect score)
4. ksun48
5. bqi343

Editorials for each of the problems will be uploaded to the respective problem pages.

We hope you enjoyed the contest, and see you next month!

We're excited to invite you to the fourth Thorndeau Logic Evaluation of the 2017-18 school year!

The TLE '17 December contest will be a 3-hour virtual contest, which will allow contestants to participate in any 3-hour window from 12:00 PM EST, December 22, 2017 to 12:00 PM EST, December 23, 2017. Please see the contest page for more details.

See you soon!

Thanks for participating in the DMOPC '17 December contest!

The winners are:

1. zhouzixiang2004
2. rpeng
3. REEmark
4. radoslav11
5. y0105w49

Editorials for each of the problems have been uploaded to the respective problem pages.

We hope you enjoyed the contest, and see you next month!

On Tuesday, December 12th, we'll be hosting the December Don Mills Open Programming Contest!

Anyone with a DMOJ account is welcome to participate, and anyone without one is welcome to register and participate.

Contestants may participate in any 3-hour window between noon EST of Dec. 12th and noon EST of Dec. 13th. Please see the contest page for more details.

See you soon!

Over the past few weeks, we've been hard at work improving DMOJ's backend for a better user experience, and today we've finally made these changes live.

Server Upgrades

The servers backing DMOJ have not received upgrades in years, and were constantly dangerously close to hitting CPU and memory limits.

After some particularly successful Black Friday shopping, we're happy to announce we've doubled the resources available to our frontend servers, and octupled those of our database. We've also split up several other services onto smaller machines dedicated to running them. Judging servers have not been updated, so expect no change in submission runtimes.

All servers have also been migrated from a New York datacenter to one in Montréal, so Canadian users should experience improved connectivity (international accesses should not be affected significantly). In our tests, the new servers render pages 20-40% faster than the old ones, and leave a lot of room for increased load during peak times.

Since this required massive changes to our networking setup behind-the-scenes, it's possible that there might be slight issues in the next few days.

New Facebook-friendly CDN

We've heard reports of DMOJ links being blocked on Facebook and Messenger, and have taken steps to resolve this. Previously, resources were being served off of dmoj.ml (for site resources) and camo.dmuser.ml (for SSL-proxied user content) — as of recently, Facebook blocks sites linking .ml TLD domains. As a result, we now serve off of dmoj.algome.me and camo.algome.me, respectively. If you use NoScript, uMatrix, or similar script-blocking browser plugins, you will have to allow these domains to use DMOJ.

Facebook issues should clear up within a few days.

Minor Judge Changes

The judge has seen a lot of work recently, largely for improving stability. Among others,

• it has been ported to Python 3, so there might be some issues popping up on complex problems
• it now disables address-space layout randomization on submissions (this means segfaults should be more reproducible)
• the sandbox permissions have been tweaked
• all JVM-based languages (Java, Kotlin, Groovy, etc.) now use -XX:+UseSerialGC
• Java 10 support has been added
• Java 7 support has been dropped, and all Java 7 submissions have been remapped to Java 8
• C11 support has been added
• Scala can be used with extends App now
• support for R has been dropped

Thanks for participating in the TLE '17 November contest!

The winners are:

1. y0105w49
2. zhouzixiang2004
3. Xylofo
4. r3mark
5. tankturtle

Editorials for each of the problems will be uploaded to the respective problem pages.

We hope you enjoyed the contest, and see you next month!

We're excited to invite you to the third Thorndeau Logic Evaluation of the 2017-18 school year!

Anyone with a DMOJ account is welcome to participate, and anyone without one is welcome to register and participate.

Thanks for participating in the DMOPC '17 November contest!

The winners are:

1. REEmark (perfect score)
2. mmaxio (perfect score)
3. y0105w49
4. zhouzixiang2004
5. kobortor

Editorials for each of the problems have been uploaded to the respective problem pages.

We hope you enjoyed the contest, and see you next month!

Additionally, mmaxio found an error in the P2 problem statement. This round will still be rated, but if anyone feels that they were affected by this mistake, then comment or contact us on Slack before the next contest, and we will cancel that your rating change from this contest.

Starting this year, there will be a couple changes to the DMOPC/DMPG.

Starting with this DMOPC:

1. The DMOPC will return to being a monthly contest, from last year's almost monthly format.
2. The top 20 Canadian High School contestants across all rounds will automatically qualify for the DMPG Gold Division.

As for the DMPG:

1. There will still be 3 divisions: Bronze, Silver, and Gold.
2. The Bronze and Silver Divisions will be open to all.
3. The Gold Division will be open to the top 20 Canadian High School contestants across the DMOPC rounds, and there will be prizes given to the top coders.

Note that this is subject to change.

On Tuesday, November 14th, we'll be hosting the November Don Mills Open Programming Contest!

Anyone with a DMOJ account is welcome to participate, and anyone without one is welcome to register and participate.

Contestants may participate in any 3-hour window between noon EST of Nov. 14th and noon EST of Nov. 15th. Please see the contest page for more details.

See you soon!

Thanks for participating in the TLE '17 October contest!

The winners are:

1. y0105w49
2. r3mark
3. zhouzixiang2004
4. bruce
5. wleung_bvg

Editorials for each of the problems will be uploaded to the respective problem pages.

We hope you enjoyed the contest, and see you next month!

We're excited to invite you to the second Thorndeau Logic Evaluation of the 2017-18 school year!

Anyone with a DMOJ account is welcome to participate and anyone without one is welcome to register and participate.

The TLE '17 October contest will be a 3-hour virtual contest, which will allow contestants to participate in any 3-hour window from 4:00 PM EDT to 11:59 PM EDT on October 27, 2017. Please see the contest page for more details.

See you soon!