UPDATED

Dear participants!

Congratulations on joining the ICPC 2020 Graph Mining Challenge powered by Huawei! All were truly amazed by the participation and quality of the solutions. Congratulations to all of the winners! You will be contacted soon about your prizes.

The competition was so fierce that ICPC U and Huawei have decided to keep the fun going by __starting a new, one-week challenge__ with all new prizes. The problem and graphs are the same, so you can build on your previous success.

__All are encouraged to participate in this challenge.__You may only win one prize from the entire ICPC Graph Mining Challenge events (all combined). If you place in multiple challenges, you will be able to pick the prize you prefer.

Many of you might have been following the Challenge tutorials on ICPC U page. If you didn’t — we’re delighted to invite you to do so in order to sharpen your problem-solving skills and applying it during this additional ICPC challenge week.

As always, ICPC U invites everyone to Train, Practice, and Perform!

What just happened? Is it going to be the same task?

How will the prizes be distributed amongst top competitors? I guess it's not really fun to get two identical phones. Also you should've told not to discuss any solutions, now many people know each others' solutions.

:)

But will participants of 3-hour challenge still receive prizes?

Are contestants who already won prizes would be out of competition in this contest?

Stupid question, but are participants allowed to cooperate?

No. That violates the rules.

Auto comment: topic has been updated by matvey.kazakov (previous revision, new revision, compare).I cannot download problem statement ....Can you give me an alternative

Go to codeforces.com/contest/{id}/problems/ and Ctrl+P the page , you should have option to save page as PDF on Chrome and FF based browser

Is there any Challenge tutorial on that page? Even Endagorion's stream is private now, which is a bit unfair to people who didn't watch him.

Challenge tutorial video was loaded on youtube channel: Day Zero: Graph Mining Challenge Tutorial with Stanislav Moiseev

Please, make contest a little bit shorter (for about 1 hour). It intersects with Global Round 9 for 55 minutes.

The contest is over now, so, can someone from top share main ideas of algorithm? Thanks in advance

My best solutions came from applying the Leiden algorithm adapted to fit the objective function, coupled with some local search/simulated annealing to get a few dozen extra points.

For a simpler solution, I found that greedily creating singleton clusters to maximize regularization on the partition given by the original Leiden algorithm works well also.

What does your function for MergeNodesSubset for Leiden look like? Did you use the γ in the pseudo-code and what is that, is it a function?

Also what was your initial temperature for SA and how did you decrease the temperature, I didn't get great scores with it compared to hill climbing and if I did it took a long time. I used temperature = 1 and decreased it linearly by .1 or .01 (and my formula for the probability looked like this: exp(delta*10000/temperature)).

I just used an existing implementation and added some extra bookkeeping data to be able to recompute the regularization quickly. The $$$\gamma$$$ is the "resolution" and is just a parameter for the objective function (for modularity, $$$\gamma = \frac1{2|E|}$$$).

For the local search, let $$$S$$$ be the current best score and $$$S'$$$ be the score after a proposed change. If $$$S > S'$$$, my algorithm would accept the change with probability $$$\min(0.02, \exp(10(S'-S))$$$. The proposed change was the best change among all possible moves for 55 randomly sampled nodes. There's no reason for choosing any of these parameters, it just worked well enough in practice.

I published post with some ideas link

Can you please keep a version of ICPC open for practice .

Thanks a lot!

how soon winners will get their prizes?? ICPCNews1

And will you pay the import tax and duties? ICPCNews1 Last time I got a prize from a Huawei contest, I was billed 189 USD in import tax and administration fees from DHL after receiving the package. There's 25% import tax in Norway, and DHL sends the bill to the receiver if the sender doesn't take care of it. I might decline the prize rather than paying the bill.