思考题 of Div2B-C Elevator Welcome back to OBCYSIO! Orange Boy has been promoted to LGM boy so this series is in an awkward situation. This problem is very easy. Consider an elevator with a max speed of v_m m/s and an acceleration of a m/s^2. When ……

anniversary 思考题 Very Easy Problem Wow! OBCYSIO has reached 50 episodes! Let's celebrate using a very popular and easy problem. Hikari and Ninetail are playing a game on an undirected graph of N nodes and M edges. They move in turns, with Hikari ……

Solved! Difficulty: Div2D-Div2E Note: this problem is drafted on 2019/7/30 by XGN and not released. It's now released on 2022/1/2 by Zzzyt under his permission. Statement Yuqi has an rooted indexed tree T of N nodes indexed from 1 to N. The n……

思考题 so easy just to prove I am not dead ESL Wulpit is a divine fox spirit. She is learning Chinese. So she doesn't understand English. One day she received an English string S of n lower case characters. XGN told her how her name would be like i……

思考题 with git Version Control You are given a DAG with N nodes and M direcitonal edges. Node 1 has 0 in degree. We define a node i is required for node j if i is in any path from 1 to j. You are given Q queries, for each query you are given A and……

Solved! Difficulty: Div2D Long time no see 思考题 Tree Traversing Hikari has a tree of N nodes. The node #1 is the root. Initially she is at node 1. She can do one of the following three operations: - Move to any adjacant node with cost 1 - M……

chemistry 思考题 Hydrocarbon Ninetail is building a tree. She has N nodes and she will assign a value from 0 to 3 to each node. All nodes with the same value are indistinguishable. Then she will connect the N nodes with N-1 edges so that they form ……

OBCYSIO Ep.41 to 43 is hosted on XGN's blog. As I am lazy to copy, please read them here

From Hexo Useful 思考题!! Replace Hikari is a cute white dragon girl. She is helping Ninetail - a fox girl, her master - correct composition.The original composition is a string S and the corrected one is another string T. Hikari claimed that……

From Hexo String 思考题!! Boggle Constructor Ninetail is a clever fox girl. She loves to play Boggle! the rules are simple: Each player searches for words that can be constructed from the letters of sequentially adjacent cubes, where "adjace……