组合数 错排

ll C[1005][1005];
void calc_Cmn()//求组合数
{
    for(int i=0;i<1001;i++)
    {
        C[i][0]=C[i][i]=1;
        for(int j=1;j<i;j++) C[i][j]=C[i-1][j-1]+C[i-1][j];
    }
}

ll Cuo[1005];
void Cuo()//求错排
{
        Cuo[1] = 0, Cuo[2] = 1;
        for (int i = 3; i <= 15; i++)
        {
                Cuo[i] = 1LL * (i - 1) * (Cuo[i - 1] + Cuo[i - 2]);
        }
}