rui_er's blog

By rui_er, history, 5 days ago, In English

1972A - Contest Proposal

Hint 1
Tutorial
Solution

1972B - Coin Games

Hint 1
Hint 2
Tutorial
Solution

1967A - Permutation Counting

Hint 1
Hint 2
Hint 3
Tutorial
Solution

1967B1 - Reverse Card (Easy Version)

Hint 1
Hint 2
Tutorial
Solution

1967B2 - Reverse Card (Hard Version)

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Hint 2
Hint 3
Tutorial
Solution

1967C - Fenwick Tree

Hint 1
Hint 2
Tutorial
Solution

1967D - Long Way to be Non-decreasing

Hint 1
Hint 2
Hint 3
Tutorial
Solution

1967E1 - Again Counting Arrays (Easy Version)

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Hint 2
Hint 3
Tutorial
Solution

1967E2 - Again Counting Arrays (Hard Version)

Thanks A_G for discovering that E2 is possible!

Hint 1
Hint 2
Tutorial
Solution

1967F - Next and Prev

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Tutorial
Solution

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By rui_er, history, 7 days ago, In English

久别无恙, Codeforces!

We are glad to invite you to take part in Codeforces Round 942 (Div. 1) and Codeforces Round 942 (Div. 2), which will start on Apr/30/2024 17:35 (Moscow time). You will be given 6 problems and 2 hours and 30 minutes to solve them in both divisions. Some problems will be divided into two subtasks.

The problems were authored and prepared by N_z__, wyrqwq, yinhy09 and me rui_er.

We would like to thank:

Score distribution:

  • Div. 2: 500 — 750 — 1500 — (1000 + 1500) — 2500 — 3500
  • Div. 1: 750 — (500 + 750) — 1250 — 1750 — (1750 + 1000) — 3500

We hope you'll like the problemset!

UPD: Congrats to the winners!

Div. 2:

  1. 3_m
  2. RinaRin
  3. eightniko
  4. liumohan
  5. golomb

Div. 1:

  1. tourist
  2. jiangly
  3. jqdai0815
  4. gamegame
  5. Kevin114514

Editorial is out.

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By rui_er, history, 13 months ago, In English

1797A - Li Hua and Maze

Tutorial
Solution (rui_er)

1797B - Li Hua and Pattern

Tutorial
Solution (rui_er)

1797C - Li Hua and Chess

Tutorial
Solution (rui_er)

1797D - Li Hua and Tree

Tutorial
Solution (rui_er)

1797E - Li Hua and Array

Tutorial
Solution (rui_er)

1797F - Li Hua and Path

Tutorial
Solution (Celtic, centroid decomposition)
Solution (rui_er, reconstruction trees)

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By rui_er, history, 13 months ago, In English

Hello, Codeforces!

AC-Automation and I rui_er are glad to invite you to participate in Codeforces Round 864 (Div. 2), which will be held on Apr/08/2023 17:05 (Moscow time). Please note the unusual start time.

This round is rated for the participants with ratings strictly lower than 2100. You will be given 6 problems and 2 hours to solve them. All the problems are prepared by AC-Automation and me.

We would like to thank:

There will be a finite number of interactive problems, so please see the guide of interactive problems if you are not familiar with it.

The main character of the problems is Li Hua.

Who is Li Hua?

Statements and editorials will be available in Chinese (Simplified) after the contest.

This is our first round. We've tried our best to make the round enjoyable. We are looking forward to your participation and hope you gain a non-negative delta in this round.

UPD1: Score distribution: 500 — 1000 — 1500 — 1750 — 2250 — 3000.

UPD2: Editorial is out.

UPD3: Statement in Chinese and Editorial in Chinese are out.

UPD4: Congrats to the winners!

Div.2:

  1. syf2008
  2. elizazh
  3. zhouzizhe
  4. psz1
  5. wnmrmr

Div.1 + Div.2:

  1. jiangly
  2. heno239
  3. SSRS_
  4. BurnedChicken
  5. Sugar_fan

Also congrats to the only div.2 participant who solves problem F: reborn2023!

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