Hello everyone. I invite you to the Amateur Round 1 (Div. 4), which already started in 07.01.2026 and ends in 15.01.2026.
You will be given 4 problems to solve. One problem will be divided into subtasks. The round will be in ICPC style.
The problems authored by zeyd1234.
I want to say "Thank you" to:
- You for participating.
Note:
If you are using Python, use sys.stdin.readline() instead of input() to prevent EOFError.
UPD: Editorial is out.
UPD2: Congratulations to the top — 10 winners:
Rules
And congratulations to top — 15 by official standing:
- PhirainEX
- ink65536
- reirugan
- krishnsai324
- potatoArmy
- Mitpro
- Furioso_Slient
- salemi1
- goririn
- Jim_X
- jowelo
- C99_x
- fatespeaker
- OAY71011
- Light_Bender
And this is a top — 10 by only WA penalty count:
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ok, ill try
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Hehe :D
You again? Hehe :D
ez +4 on A ...
You mean A easy? A really easy. But C a bit harder, and B2 too.
B2 is ez tho
But you should find the idea. And this is Div 4. ofc this is easy for you.
Soon i will come with teammate, and with more competitive problems.
also i asked a question (problem C):
If User1 posts id 1 and id 2
Remove id 1
Then what would User1's next post id be? (id1 or id3)
also problem B: l<=r, then in sample: l=500,r=150 (bruh)
Sorry, i don't have enough time to work and check all guestion in one time. At least, i answered.
but i solved it now!
But i answered to your guestion a hour ago.
i was eating dinner
A hard.
5 attempt to pass A
I would like to ask how to create problems and contests on CF?
Use Polygon, I also made my own contest, try it out here!
It ends.
Ohh, virtual participate it!
The B2 problem can be made even more challenging — simply add multiple test cases, and in theory, the number of these test cases can range from 1e5 to 1e6.
Ok, i will try to do tasks more difficult and challenging in next contest.
A is very very bad
B is bad
C is really amazing
This is my first contest. I will try to imagine better problems.
And, A, B is bad because Easy, or?
although easy but weird input format in A
Problem Z is kinda hard...
You shouldn't solve it, i will describe this task in Editorial.
it is eziest :)
Glad to take part in the competition.
Contest already started, but submissions can't be judged right now, because of Hello 2026 Round.
will the time penalty counted for final standing or number of WA penalty?
I will don't count time penalty, only WA penalty. I will count it manually and select first 5 person.
as a newbie this was a good contest for me. tho i couldn't solve C. my target was just A & B. Thanks for the contest
I'm glad that you enjoyed the contest.
In B1 input says l <= r but not even samples satisfy it.
Thats feature:
I wanted to make a task that tested attention and edge case testing. But I accidentally added this.
At least replace $$$l\leq r$$$ with $$$l,r$$$...
Also, why did 20+ guys solved Z? Is the problem statement leaked or something?
Bruh, IDK how, but they see that Z == A with one incorrect test case. But i started the contest, so i don't able to delete the task, so i renamed the task name and say:
Don't do this.
And, If I change it, I'll have to do the same thing again as with A. It's easier for me to start a new contest than this. So better to don't this. Sorry.
Did you remove problem Z?
Yes. Because that shouldn't be a problem.
Okay. Nice! I will join. Thank you for this, zeyd1234
:)
Hey! We can make a Div. 4/Div.3 round together! I have already got some ideas for problems, I can test for your problems, you test for my problems! I make editorial, you make announcement! Sounds good?
When you were creating the contest, it was your intention in B2 to create a vector with all the armstrong numbers between 1 to 1e8?
im just a newbie but i would say it was qute a solid contest if it is yours first as you have said. But the input on A was a little bit strange, however i will not lie to you, studying data structures i think we have to discover how to handle those weird inputs.
Yes, you are right, but please, don't say anything about solutions there, give other people a chance.
On problem B1 you wrote the input constraint as $$$1 \leq l \leq r \leq 10^6$$$, where in test case 2 the input given is
500 150, this clearly violates your input constraint, so it would be better if you wrote the input constraint such as $$$1 \leq l, r \leq 10^6$$$, this would make it possible to give test case with invalid range while also not violating the problem input constraint.Sorry, thats clearly my mistake, but i don't able do edit problem when contest starts. So i thinked that you will able to see this and do a right solution.
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Please, join to this discord group:
https://discord.gg/fSgCnbeF
Fun Fact: I know PhirainEX from his contest on a Chinese coding platform.
Wasn't the standing system was like counting number of WA on the problem or the time when someone did ?
If you want, i can add that standing too.
yea please
it was a good contest
Thanks
The contest was not bad.
Problems A and C were super easy. I didn’t like the solution for B.
Also, having a leaderboard doesn’t make sense for this contest. A newbie who participates on the first day would outrank an LGM who participates at the end.
If the duration of the contest were 2 hours, it would make sense.
Ok, in other contests i will do a better system, maybe put 3 hours to solve or something else.
Agreed but i think so that must be Ac problem at any contest for newpies . I don't like destroying people