$\mathcal A$ is a collection of combinatorial objects. => $\mathcal A$ and $\mathcal B$ are combinatorically isomorphic if there exist a size-preserving bijection between $\mathcal A$ and $\mathcal B$ Q1 Prove that number of Dyck Paths D_{n-1} equa……

思考题 of math again Slime Legend II In the world of fantasy, there lives N+1 types of monsters indexed from 0 to N. Each monster can be represented by an integer pow_i - their power. And specially, type 0 is SLIME. Slime has a special ability to "……

2019多校 Diary Round 1 各位好，我是（问gwq骗取了贵studios的admin的账号和密码的）syr。 （因为blog内容要公开，我就写得政治正确一点吧。。。） Preparation 在20190721的比赛前半个小时，syr/xgn/monkey king终于拿到了他们的账号 syr开通了skype，加入群聊“多校……

Today is the first day of MUTC!!! On this site there will be diary about our team (team0248). Good luck! MUTC is a series of OI contests held every year usually 10 contests in a row.

In a recent Codeforces Contest Codeforces Global Round 4, the Orange Boy MonkeyKing got a T-shirt by getting rank 449. BEST RATING CHANGE

You are given something, what is it? You don't know, but you are curious about it. You want to know what it is, but you can't. It made you unpleasant, you are somewhat angry. 当你的野心还撑不起你的才华时，就应该静下心来评论一下。 Formally,you are g……

思考题 that is quite easy FACT ZJS likes to show off his wonderful calculator. His calculator can do FACT operation which means can divide an integer to some primes' products. For example, Fact(30) will display 2\times3\times5 which is a string of ……

思考题 that is easier than #14 Sort and Sort and Sort and Sort You are given an integer array A of length N. And you are given Q queries. For each query, you are given Li and Ri. You need to find out the sum of products of adjcent numbers in the so……

思考题 specially Orange Boy And Orange Program Orange Boy is a programmer of Sunway TaihuLight. One day he wrote the following program to test the super computer: int n; int a[100005]; int getAns(int l,int r,int x){ int ans=0; for(int i=l;i

思考题 on trees again Tree You are given a weighted undirected tree T of N nodes. Each edge i has a weight W_i. Assume that the edges you need to travel from node i to j is E_1,E_2,E_3...E_k then we define $c_{i,j}=(-1)^k \times \sum {i=0}^kW{E_i}F……