分治FFT/NTT

粘板子：

#include
#include
#include
using namespace std;
typedef long long ll;
const int MOD = 998244353;
const int N = 100050;
const int M = N*3;
template
inline void read(T&x)
{
    T f = 1,c = 0;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){c=c*10+ch-'0';ch=getchar();}
    x = f*c;
}
templateinline void Mod(T&x){if(x>=MOD)x-=MOD;}
int fastpow(int x,int y)
{
    int ret = 1;
    while(y)
    {
        if(y&1)ret=1ll*ret*x%MOD;
        x=1ll*x*x%MOD;y>>=1;
    }
    return ret;
}
int inv(int x){return fastpow(x,MOD-2);}
int to[M],lim,L,LL[M];
void init(int len)
{
    lim=LL[2]=1;
    while(lim1,LL[lim<<1]=LL[lim]+1;
}
void get_lim(int len)
{
    lim = len,L = LL[len];
    for(int i=1;i<=lim;i++)to[i]=((to[i>>1]>>1)|((i&1)<<(L-1)));
}
void ntt(int*a,int len,int k)
{
    for(int i=0;i)
        if(i<to[i])swap(a[i],a[to[i]]);
    for(int i=1;i1)
    {
        int w0 = fastpow(3,(MOD-1)/(i<<1));
        for(int j=0;j1))
        {
            int w = 1;
            for(int o=0;oMOD)
            {
                int w1 = a[j+o],w2 = 1ll*a[j+o+i]*w%MOD;
                Mod(a[j+o] = w1+w2);
                Mod(a[j+o+i] = w1+MOD-w2);
            }
        }
    }
    if(k==-1)
    {
        for(int i=1;i>1;i++)swap(a[i],a[len-i]);
        int Inv = inv(len);
        for(int i=0;iMOD;
    }
}
int a[M],b[M],c[M];
int f[M],g[M],n;
void cdq(int l,int r)
{
    if(l==r)return ;
    int mid = (l+r)>>1;
    cdq(l,mid);
    get_lim(2*(r-l+1));
    for(int i=0;i0;
    for(int i=0;i<=mid-l;i++)a[i]=f[l+i];
    for(int i=1;i<=r-l+1;i++)b[i]=g[i];
    ntt(a,lim,1),ntt(b,lim,1);
    for(int i=0;i<=lim;i++)c[i]=1ll*a[i]*b[i]%MOD;
    ntt(c,lim,-1);
    for(int i=mid+1-l;i<=r-l;i++)Mod(f[i+l]+=c[i]);
    cdq(mid+1,r);
}
int main()
{
//    freopen("tt.in","r",stdin);
    read(n);init(n<<1);f[0]=1;
    for(int i=1;i)read(g[i]);
    cdq(0,lim-1);
    for(int i=0;i"%d ",f[i]);
    puts("");
    return 0;
}

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转载于:https://www.cnblogs.com/LiGuanlin1124/p/11162009.html