矩阵快速幂

struct Matrix{    ll m[sz][sz];};Matrix Mul(Matrix a,Matrix b){    Matrix c;    memset(c.m,0,sizeof(c.m));    for(int i=0; i<sz; i++)        for(int j=0; j<sz; j++)            for(int k=0; k<sz; k++)            {                if(a.m[i][k]==0||b.m[k][j]==0) continue;                c.m[i][j]=(c.m[i][j]+a.m[i][k]*b.m[k][j]+mod)%mod;            }    return c;}Matrix fastm(Matrix res, Matrix a,ll n){    while(n)    {        if(n&1)            res = Mul(res,a);        n>>=1;        a = Mul(a,a);    }    return res;}Matrix init()//关系阵{    Matrix pp;    return pp;}