Hello, Codeforces!

We are glad to invite you to the Codeforces Round #572, which will be held on Friday, 5 July at 18:05. The round will be rated for both divisions (as this time we thanked MikeMirzayanov).

Round was prepared by us, antontrygubO_o and kefaa2. This is our first round, and, as we hope, not the last one!

A lot of thanks to arsijo for the excellent coordination of the round, gepardo, GandalfTheGrey, progmatic2, zoomswk, ecnerwala, AllCatsAreBeautiful, DmitryGrigorev, Markellonchik, dasfex, Taran_1407, slicedclementines, DenisPushkin, austrian_artist, mmello, sas4eka for the testing and valuable comments, and to Mike MikeMirzayanov Mirzayanov for the amazing platforms Codeforces и Polygon. (please rated)

Participants in each division will be offered 6 problems and 2 hours to solve them. We strongly recommend reading statements of all problems! The scoring distribution will hopefully be announced before the round begins.

We wish you good luck and high rating!

UPD1: Shortly after the contest, we'll be on the community Discord server to discuss the tasks.

UPD2: Slight corrections: participants in Div $$$1$$$ will be offered $$$5$$$ problems, one of which will have $$$2$$$ subtasks, while participants in Div $$$2$$$ will be offered $$$6$$$ problems, one of which will have $$$2$$$ subtasks. Please note that subtasks will be unusual this time and will differ not only by constraints.

UPD3:

Scoring distribution of Div $$$2$$$ round: 500 — 1000 — 1250 — (500 + 1250) — 2250 — 2750

Scoring distribution of Div $$$1$$$ round: (250 + 750) — 1250 — 1750 — 2250 — 2500

UPD4: Editorial

UPD5 Congrats to winners!

Div 1:

1. Um_nik

2. ugly2333

3. Radewoosh

4. Marcin_smu

5. Endagorion

Div 2:

1. esbee

2. handsomeIvan

3. philologist

4. teamskiy

5. NeoGul

Close to New Year, I think, a lot of competitive programmers were setting their goals for the year 2019. Some posted their goals, some not, but most of them were related to their rating ambitions (like becoming IGM by end of 2019). I think that the ACM ICPC final 2019 is a good day for setting the goals for ACM ICPC season 2019-2020.

I know that studying and training is a much more productive way of getting closer to your goals than dreaming and talking, but I feel like reading which goals other participants set for them may be really motivating and inspiring.

Feel free to share your goals with the community, no matter if you are a disappointed participant from this year final or a student of a university which has never been to final before!

Yesterday I saw the announcement of the contest Code Mutants on Codeforces, it said contest will take place today (19th February). I went through the announcement, it said:

"Top 3 contestants will be rewarded with 250 Laddus!! from CodeChef.Some of the top contestants will be selected for onsite round where prizes worth 10,000 INR are waiting for you!!"

I thought: "Cool! I definitely should try it, I feel inspired!"

So I felt inspired and went to the CodeChef. In announcement there, I saw the following:

Hoping to get to onsite, I filled in this form!

Then, the contest started. Tasks turned out to be very interesting! Even more impressive was innovative Tex formatting:

After I solved the first task, I tried to submit it and clicked Submit. However, it was testing too long. "Maybe it's TL?" — I asked myself. After it was testing for 5 more minutes, I dropped that idea.

That was kinda strange. I went to my submissions of that problem and discovered that I had no submission for it. Moreover, after I tried to send the solution 5 more times, I still had no submission for it. However, after I got too nervous, I got the following message from Codechef:

So it was receiving my submissions, just wasn't displaying them anywhere. Still happy about the great contest, I went to the contest page and saw that tasks were so hard that nobody managed to solve a single problem!

However, it turned out that some solutions still were tested, though not displayed there. I went to the scoreboard and saw that somebody managed to submit a few problems. However, there were some cheaters, who, as their penalty indicates, submitted problems even before the contest started.

It got really suspicious. I went to the announcements, expecting to see the message telling about technical issues, but here is what I saw:

Nice! That's exactly what would help me now.

However, later they acknowledged that they experience some technical issues:

Anyway, I really enjoyed the contest! I have never laughed so much during the actual online competition. Tell about the contests that you enjoyed!

Thanks for attention

P.S. I didn't want to imply anything bad about the problem setters or to express any disrespect to organisers: they still have done a lot of work. Just wanted to share the best contest of my life impressions!

After 6 months without contests, CsAcademy is finally back!

https://csacademy.com/contest/fii-code-2019-round-1

I am just curious.

Suppose some problem has a randomized solution which fails with probability at most . If it has, say, 100 tests, the probability of failing some of them is about . Therefore, once in 10⁴ it may happen that correct randomized solution doesn't pass.

Has anyone experienced anything like that? Maybe even the exact solution that didn't pass got AC after submitting it the second time? Or am I getting something wrong?