NTT模板

const int mod  = 1004535809;
const int maxn = 262144;
const int G    = 3;
int Qpow( int a , int b , int m )
{
    if ( b<0 )
    {
        b = -b;
        a = Qpow( a , m-2 , m );
    }
    int res = 1;
    while ( b )
    {
        if ( b&1 )
            res = 1LL*res*a%m;
        a = 1LL*a*a%m;
        b = b>>1;
    }
    return res;
}
int rev[maxn];
void Get_rev( int bit )
{
    for ( int i=0 ; i<(1<<bit) ; i++ )
        rev[i] = (rev[i>>1]>>1)|((i&1)<<(bit-1));
}
void NTT( int *a , int n , int dft )
{
    for ( int i=0 ; i<n ; i++ )
        if ( i<rev[i] )
            swap ( a[i] , a[rev[i]] );
    for ( int step=1 ; step<n ; step<<=1 )
    {
        int wn = Qpow( G , dft*(mod-1)/(step*2) , mod );
        for ( int j=0 ; j<n ; j+=step<<1 )
        {
            int wnk = 1;
            for ( int k=j ; k<j+step ; k++ )
            {
                int x = a[k]%mod;
                int y = 1LL*wnk*a[k+step]%mod;
                a[k] = (x+y)%mod;
                a[k+step] = ((x-y)%mod+mod)%mod;
                wnk = 1LL*wnk*wn%mod;
            }
        }
    }
    if ( dft==-1 )
    {
        int inv = Qpow( n , mod-2 , mod );
        for ( int i=0 ; i<n ; i++ )
            a[i] = 1LL*a[i]*inv%mod;
    }
}