nexthexonextbutterflyvolantisyearnyiliashokaindigoapollolandscapecactusmateryicarusfluidmaterial 生成树一个无向图的生成树指的是从图中选若干边构成边集，全部点构成点集，使得这个边集加上点集恰好是一棵树。 生成树计数一个无向无权图(允许重边不允许自环)的邻接矩阵为g，显然这是一个对称矩阵，g[u]...

nexthexonextbutterflyvolantisyearnyiliashokaindigoapollolandscapecactusmateryicarusfluidmaterial nameEasy Math Problem descirptionOne day, Touma Kazusa encountered a easy math problem. Given n and...

nexthexonextbutterflyvolantisyearnyiliashokaindigoapollolandscapecactusmateryicarusfluidmaterial min25筛是什么min25筛是一种筛法，他能以亚线性的时间复杂度筛出一类函数的前缀和 定义一部分符号$M(x) x\gt1$代表$x$的最小质因子 我们再设$P_j$为第$j$小的质数,...

nexthexonextbutterflyvolantisyearnyiliashokaindigoapollolandscapecactusmateryicarusfluidmaterial 中间结论$$f_n = \sum_{i=0}^n (-1)^i {n \choose i} g_i\Leftrightarrowg_n = \sum_{i=0...

nexthexonextbutterflyvolantisyearnyiliashokaindigoapollolandscapecactusmateryicarusfluidmaterial ###name种花家的零食 ###descirption在很久以前，有一颗蓝星，蓝星上有一个种花家。种花家有1到n共n包零食，同时种花家的兔子又有1到n共n个朋友(比如毛熊，鹰酱，脚盆鸡等）。昨天，...

nexthexonextbutterflyvolantisyearnyiliashokaindigoapollolandscapecactusmateryicarusfluidmaterial 有这样一类问题，他们的形式常常是这个样子$$\begin{aligned}\sum_{i=1}^n{f(i)[gcd(i,j)=1]}\end{aligned}$$ 我们来对...

nexthexonextbutterflyvolantisyearnyiliashokaindigoapollolandscapecactusmateryicarusfluidmaterial ###namearray ###descirptionYou are given an array $a_1,a_2,…,a_n(∀i∈[1,n],1≤a_i≤n)$. Initially, eac...

nexthexonextbutterflyvolantisyearnyiliashokaindigoapollolandscapecactusmateryicarusfluidmaterial ###name ###descirption ###input ###output ###sample input ###sample output ###toturial先来看一个简单的变形$...

nexthexonextbutterflyvolantisyearnyiliashokaindigoapollolandscapecactusmateryicarusfluidmaterial ###nameString ###descirptionTom has a string containing only lowercase letters. He wants to choose ...

nexthexonextbutterflyvolantisyearnyiliashokaindigoapollolandscapecactusmateryicarusfluidmaterial ###nameMeteor ###descirptionhough time passes, there is always someone we will never forget.“The pr...