Grand Archive

What harbor can receive you more securely than a great library?

Problem Sets

CCPC 2018 Jilin Onsite [Solution], Problem I and K are dedicated to Mr. Kazuki Takahashi, Dr. Richard Garfield and the people who ceaselessly bring happiness and integrity to this world.

National Olympiad of Informatics 2019, Problem A is dedicated to my beloved girlfriend.

Asia East Continent Final 2021, Problem J is dedicated to Mr. Hidetaka Miyazaki and those bring us colorful flavors through their masterpieces.

Chinese Girl's Mathematic Olympiad 2023, Problem 8 is a combinatorial gem built on the Erdős–Szekeres theorem.

Asia East Continent Final 2024, Problem I is built on a corollary of the JCDCGGG paper, which is exactly the hidden point set of a staircase polygon.

Random Pieces

56 Interesting Problems from Andrew Stankevich Contest [Chinese]. This is the problems selected by me from ASC during the past 20 years with my personal solution.