mat 加速模板

垃圾vector nmsl

struct mat
{
  static const int md=1e9+7;
  ll a[4][4];
  mat()
  {
    memset(a,0,sizeof(a));
  } 
  mat(int x)
  {
    memset(a,0,sizeof(a));
    a[0][0]=a[1][1]=a[2][2]=a[3][3]=1;
  } 
  ll* operator[](int x)
  {
    return a[x];
  }
  mat operator+(mat r)
  {
    mat res;  
    for (int i=0; i<4; ++i)
    {
      for (int j=0; j<4; ++j)
      {
        res[i][j]=(a[i][j]+r[i][j])%md;
      }
    }
    return res;
  } 
  mat operator-(mat r)
  {
    mat res;
    for (int i=0; i<4; ++i)
    {
      for (int j=0; j<4; ++j)
      {
        res[i][j]=(a[i][j]-r[i][j]+md)%md;
      }
    }
    return res;
  } 
  mat operator*(mat r)
  {
    
    mat res;
    for(int i=0; i<4; i++)
      for(int j=i; j<4; j++)
        for(int k=i; k<=j; k++)
          res[i][j]=add((res[i][j]+  a[i][k]*r[k][j] )%md,md);
    return res;
  }
};