We would like to invite you to participate in the 2018 Arab Collegiate Programming Contest (ACPC 2018) that was held on the 11th of November 2018 in Sharm El Sheikh, Egypt.

The contest will be available on 19.11.2018 19:00 (Московское время)

The contest was prepared and/or tested by Thrax, Badry, Med0b1011, BitHashTech, _AymanSalah, Saeed, Mhammad1,justHusam,AhmedSoliman ,Safrout, Mohammad_Yasser, m_5airy7,abdelkarim, hardw3ll,Lvitsa, MostafaAbdullah and others.

Edit : The contest has been delayed by 24 hours so not to clash with a CF round.

Is it ACPC as mentioned here, or ECPC as mentioned in GYM?

Maybe it is another contest as the starting time of the ECPC is 17 November 20:05(UTC+6) but The ACPC will start on November 18 , 22:00(UTC+6)

ACPC. Both are getting posted.

Clashes pretty hard with #522. Is there any chance of moving it later?

Thanks for notifying us.

We've moved the contest by 24 hours.

How to solve A?

SpoilerCentroid Decomposition

You can also solve it with a fenwick + small to large merge

Or FFT + centroid :)

How to pass G without a stupidly optimized Mo?

Dynamic segment-tree for every possible D.

How to solve K (using dp)?

SpoilerHint #1: If N is 1000, and K is 10^4, what is the answer? Notice as N is large, you will be forced to make more than K subarrays. Infact, the bound on N is smaller.

Hint #2: If you keep track of all prefix arrays with their corresponding modulo (which is 0,1 or 2), can you figure out how many array are divisible by 3? It does when you go back to yourself, if you have a prefix array at index i with sum k modulo 3, and another at index j with the same k modulo 3, then the array from j to i is divisible by 3.

If you want a code PM me.

Any hint for problem D

Dull Chocolates?SpoilerCan you solve it if it's a 500x500 grid? Use 2D sums.

In the current version, how many points do you have? How many are redundant? check co-ordinate/grid compression.

Can you please explain how to implement grid compression ?

We will post an editorial soon. :)

Sorry about the delay, the editorial can be found here : https://codeforces.com/blog/entry/63699

I still can't find the official scoreboard for the contest. I was hoping I can find it here as ghost results :-(

There was an updated scoreboard posted on the ACPC FB page. Most probably it will get updated on the ICPC website soon though.