思考题 in mid autumn This is hard version of Ep.58. If you prefer easier problems, please visit this link. LianLi Branches II Wulpit has drawn n nodes(indexed from 1 to n) and n-m edges on paper for homework assignments. They form m rooted trees (a……

Solved! Difficulty: Div2 C 思考题 in mid autumn This is easy version of Ep.59. If you prefer harder problems, please visit this link. LianLi Branches Wulpit has drawn n nodes(indexed from 1 to n) and n-m edges on paper for homework assignment……

Solved! Difficulty: Div2B 1 problem for div3 participants. Beautiful Dice Painting When Epis is bored, she will draw dices. The canvas contains n*n dots. Initially they are all white. You need to paint exactly v dots black so that the final c……

trivial 思考题 I am Banach This is a classic problem by Banach nearly without any change. There are N boys and M girls. Each boy loves a single girl and each girl loves a single boy. Your task is to divide the boys into two groups A_0 and A_1 and t……

Starting from today, we will try to write tutorials and rate difficulties for already solved Orange Boy Can You Solve It Out?(OBCYSIO) problems and separate them from unsolved/unsolvable ones. There's a new category called Solved OBCYSIO and you ca……

思考题 during OI recovery Rubbish Problem Maybe you have heard of the evil problem Hilbert's Hedge Maze and here's another very fun problem! You have n items arranged in rows. Each row contains r items and the items are arranged from left to right,……

思考题 with hard-to-write checker and interactor Peripheral Lightup! Note: this is not a traditional problem. Follow the instruction in the statement to help construct your solution Lead-in: The Palace is celebrating a festival with LED lights! Ins……

Solved! Difficulty: Div2C 思考题 in dreamland Construct it XGN dreamt about the following problem when sleeping: You are given a positive integer n (2\leq n\leq 10^8). Output an arithmetic expression that yields the value n with the following……

思考题 which is an adaptation from a popular problem. The source problem is very popular. IDK if this adaptation has been made or not. Adaptation There are N people indexed from 1 to N in a room. Each of them is given a hat of a random color. The t……

Finally some geometry! Maybe very easy though. Currently I am undergoing the College Entrance Exam(GK) so I don't have many ideas for Competitive Programming problems. This problem is inspired by some math problem in GK Simulation. Of course, this ……