### MarkBcc168's blog

By MarkBcc168, 9 months ago,

Hello Codeforces,

We are glad to invite you to Codeforces Round 807 (Div. 2), which will be held on Jul/15/2022 16:35 (Moscow time). As usual, the round will be rated for participants with ratings lower than 2100, while those who have higher ratings are encouraged to participate unofficially. Please note the unusual start time.

You will be given 6 problems to be solved in 2 hours and 15 minutes. There may or may not be interactive problems, so you are encouraged to prepare in case they do appear by reading this guide.

The round is authored by abc241 and me, while joining us is also inwbearX who contributed significantly to the preparation. This is our first time setting rounds in Codeforces, and it wouldn't be possible if there were no support from the following people.

The score distribution is $500$ — $1000$ — $1250$ — $1750$ — $2500$ — $3000$.

We are looking forward to your participation. Good luck and enjoy our round!

Update: the editorial is up!

Update 2: Winners!

Div. 2

Div. 1 + Div. 2

• +280

By MarkBcc168, history, 9 months ago,

Thanks for participating. We apologize for problem F that has appeared before. Still, we hope you all enjoy our round!

## 1705A - Mark the Photographer

Author: MarkBcc168

Hint 1
Hint 2
Tutorial
Code

## 1705B - Mark the Dust Sweeper

Author: MarkBcc168

Hint
Tutorial
Code

## 1705C - Mark and His Unfinished Essay

Author: MarkBcc168

Hint 1
Hint 2
Hint 3
Tutorial
Code

## 1705D - Mark and Lightbulbs

Author: MarkBcc168

Hint 1
Hint 2
Hint 3
Tutorial
Code

## 1705E - Mark and Professor Koro

Author: abc241

Hint 1
Hint 2
Hint 3
Hint 4
Tutorial
Code (Bitsets, by errorgorn)
Code (Lazy Segment)

## 1705F - Mark and the Online Exam

Author: MarkBcc168

Unfortunately, a harder version of this problem has appeared in a Chinese contest here and here. You can look at their solution here. We thank many contestants who pointed it out.

Hint 0
Hint 1
Hint 2
Hint 3
Hint 4
Tutorial
Code
• +121