We will hold AtCoder Beginner Contest 391.
- Contest URL: https://atcoder.jp/contests/abc391
- Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20250201T2100&p1=248
- Duration: 100 minutes
- Writer: sotanishy, toam, physics0523
- Tester: math957963, cn449
- Rated range: ~ 1999
- The point values: 100-200-300-400-450-500-600
We are looking forward to your participation!








The first AtCoder race in this lunar year!
Good luck!
As the weakest one of all the pigeons, good luck!
this contest was brutal
Is F some kind of a well-known problem or it's just really simple? Didn't solve it, but 1k+ submissions is quite a lot for F.
https://github.com/joric/interviewbit/blob/master/programming/graph-data-structure-and-algorithms/smallest-sequence-with-given-primes.md
Is D really so easy to implement? I keep getting WA on 21 testcases :(
Help me out please. Where am I going wrong? Submission
This fact simplifies the implementation significantly:
Let
col[i]be the row-indices of all blocks in columni, sorted in ascending order. The time at which the k-th row disappears is the maximum of the k-th element, among all columns, i.e.max(col[i][k]) for all i=1..W.So ,is rank 1 legit?
Why does everyone think E is easier than D but I do not think so?
For me, E is a simple divide and conquer problem. But I didn't bother to try D despite having 1 hour left, because of its complexity.
G seems like a too well known problem for 200+ submissions.
I went through all of the Indian Submissions and almost all seem AI generated. Hopefully the admins take strict action.
Yeah I realised that when I saw low rated people solving G within 20 minutes and most of my friends not being able to solve it.
why is the editorial of problem D with complexity O(n log n)? it can be solved in O(n)
as for the code:
with complexity O(n+q)
in fact, we don't need to sort
Hey i have a question. I have heard lots of people talk about how good the ABCs are ? Can anyone tell me why they are good ? Thanks. I am a newbie so dont know a lot of stuff
check this: video by maroonrk
Thanks this was helpful
How to do E ?