fo0Old的博客

const int mod=998244353; //改modstruct matrix { int n,m; ll ma[105][105]; matrix(int x,int y):n(x),m(y) { memset(ma,0,sizeof(ma)); } matrix operator*(matrix& x) {

一维树状数组 长度为nnn的序列: a1,a2,⋯ ,ana_1,a_2,\cdots,a_na1​,a2​,⋯,an​ 一阶差分与前缀和 一阶差分数组: di=ai−ai−1(a0=0)d_i=a_i-a_{i-1}\qquad(a_0=0)di​=ai​−ai−1​(a0​=0) 考虑序列aaa第mmm项: am=∑i=1mdia_m=\sum\limits_{i=...