We will hold AtCoder Regular Contest 149.

- Contest URL: https://atcoder.jp/contests/arc149
- Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20221002T2100&p1=248
- Duration: 120 minutes
- Number of Tasks: 6
- Writer: maspy
- Tester: Nyaan, potato167
- Rated range: — 2799

The point values will be 300-500-500-700-700-900.

We are looking forward to your participation!

hope all of you have fun!

(upd: What an interesting contest! the solution of B is very interesting!)

Hope you all have a good time in this competition！

Hope to solve 3 problems

Succeeded!

thanks

Problems were interesting.

Hey i have never participated in ARC rounds. Are they harder than normal beginner contests?

What is the minimum codeforces rating one should have to solve 2 problems in most of the contests?

Yes ARCs are harder than ABC contests and it's rating range is until 2799 but ABC's rated range is until 1999, Also I don't think CF rating is a good criterion for atcoder contests so I can't answer your second question.

C was a good problem, but my algorithm only works with $$$n \geq 9$$$. therefore, i have to calculate all the situations for $$$n \in [3, 8]$$$ and add it to my code :(

I am luckier than you.I have to calculate the situations for n=3&&n=5.

I'm even luckier, I only need to calculate the situation for $$$n=3$$$.

D harder than normal, but it's still a great contest. Hope a more banlanced contest next time!

Problem D is similar to this problem.

my nlogn solution

It is difficult for me to understand the official solution of problem D, especially the "symmetry" part and the "spanning a directed edge" part.

Would anyone like to share your editorial of this problem? Thank you so much.

Screencast

Such testcase does not exist in D, where the last move will put something to coordinate 0. Example case:

`1 1 5 5`

https://polygon.codeforces.com/p4Aw6L8/Happy_Polygon/unions

In problem A, X is a positive integer less than 10^N and N can go upto 10^5 which means X is a positive integer less than 10^(10^5). What should I conclude from this?

It means X is a string of digits with string length <= 10^5.

In Problem C, instead of looking for multiples of 3, I looked for getting the sum of n^2 (for n = odd cases because n^2 is odd, so the sum of 2 numbers means one of them is odd) and n^2-1 (for n = even cases because n^2-1 is odd.)

Both n^2 and n^2-1 are NOT prime.

I am so happy that I've got a rating rise of more than 900 points.

(As my surprise, Atcoder's discuss in in Codeforces.)