#include<bits/stdc++.h>
using namespace std;
#define int long long
#define fu(i,j,k) for(int i=j;i<=k;i++)
#define fd(i,j,k) for(int i=j;i>=k;i--)
const int N=8e5+10,P=998244353;
int qpow(int a,int b){int ans=1;for(;b;b>>=1,a=a*a%P)if(b&1)ans=ans*a%P;return ans;}
int a[N],b[N],d[N];
void ntt(int s[],int n,int x)
{
	if(n==1)return;
	int s1[n/2],s2[n/2];
	fu(i,0,n/2-1)s1[i]=s[i*2],s2[i]=s[i*2+1];
	ntt(s1,n/2,x*x%P);ntt(s2,n/2,x*x%P);
	for(int i=0,xi=1;i<n/2;i++,xi=xi*x%P)
	{
		s[i]=(s1[i]+s2[i]*xi)%P;
		s[i+n/2]=((s1[i]-s2[i]*xi)%P+P)%P;
	} 
}
int merge(int s1[],int len1,int s2[],int len2,int s[])
{
	int D=1;while(D<len1+len2-1)D<<=1;
	fu(i,len1,D-1)s1[i]=0;
	fu(i,len2,D-1)s2[i]=0;
	int inv=qpow(D,P-2),x=qpow(3,(P-1)/D);
	ntt(s1,D,x);ntt(s2,D,x);
	fu(i,0,D-1)s[i]=s1[i]*s2[i]%P;
	int inv1=qpow(x,P-2);
	ntt(s,D,inv1);
	fu(i,0,len1+len2-2)s[i]=s[i]*inv%P;
	return len1+len2-1;
}
int divide(int s[],int l,int r)
{
	if(l==r){s[0]=1;s[1]=d[l];return 2;}
	int tmp1[N],tmp2[N];
	int mid=(l+r)>>1;
	int len1=divide(tmp1,l,mid),len2=divide(tmp2,mid+1,r);
	return merge(tmp1,len1,tmp2,len2,s);
}
signed main()
{
	int n;cin>>n;
	fu(i,1,n)cin>>d[i];
	int s=0;fu(i,1,n)s+=d[i];
	divide(a,1,n);
	int ans=0,sum=1;
	fu(i,0,n)
	{
		ans=(ans+sum*a[i])%P;
		sum=sum*(i+1)%P*qpow(s-i,P-2)%P;
	}
	cout<<ans;
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll mod=998244353;
ll qpow(ll a,ll b){
	ll ans=1;
	for(;b;b>>=1,a=a*a%mod)if(b&1)ans=ans*a%mod;
	return ans;
}
int r[2000010];
void NTT(vector<ll> &a,ll n,ll x){
	for(int i=0;i<n;i++)if(i<r[i])swap(a[i],a[r[i]]);
	for(int m=2;m<=n;m<<=1){
		ll g1=qpow(x,n/m);
		for(int i=0;i<n;i+=m){
			ll gk=1;
			for(int j=0;j<m/2;j++){
				ll x=a[i+j],y=a[i+j+m/2]*gk%mod;
				a[i+j]=(x+y)%mod;a[i+j+m/2]=(x-y+mod)%mod;
				gk=gk*g1%mod;
			}
		}
	}
}
vector<ll> solve(vector<ll> a,vector<ll> b){
	if(a.empty()||b.empty())return {0};
	int n=1;
	while(n<a.size()+b.size()-1)n<<=1;
	a.resize(n);b.resize(n);
	ll x=qpow(3,(mod-1)/n);
	for(int i=0;i<n;i++)r[i]=r[i/2]/2+(i&1)*n/2;
	NTT(a,n,x);NTT(b,n,x);
	for(int i=0;i<n;i++)a[i]=a[i]*b[i]%mod;
	NTT(a,n,qpow(x,mod-2));
	ll inv=qpow(n,mod-2);
	for(int i=0;i<n;i++)a[i]=a[i]*inv%mod;
	return a; 
}
vector<ll> f(vector<ll> &a,int l,int r){
	if(l==r)return {1,a[l]};
	int mid=(l+r)>>1;
	return solve(f(a,l,mid),f(a,mid+1,r));
}
int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	int n;
	cin>>n;
	vector<ll> a(n);
	ll cnt=0;
	for(int i=0;i<n;i++){
		cin>>a[i];
		cnt+=a[i];
	}
	vector<ll> b=f(a,0,n-1);
	ll ans=1,s1=1,s2=1;
	for(int i=1;i<=n&&i<b.size();i++){
		s1=s1*i%mod;
		s2=s2*(cnt-i+1)%mod;
		ans=(ans+b[i]*s1%mod*qpow(s2,mod-2)%mod)%mod;
	}
	cout<<ans;
	return 0;
}

改了一下码风

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll M=8e5+10,P=998244353;
inline ll qpow(ll a,ll b){
	ll res=1;
	for(;b;b>>=1,a=a*a%P){
		if(b&1){
			res=res*a%P;
		}
	}
	return res;
}
inline void NTT(ll a[],ll n,ll x){
	if(n==1)return;
	ll a1[n/2],a2[n/2];
	for(ll i=0;i<n/2;i++){
		a1[i]=a[2*i];
		a2[i]=a[2*i+1];
	}
	NTT(a1,n/2,x*x%P);
	NTT(a2,n/2,x*x%P);
	ll xi=1;
	for(ll i=0;i<n/2;i++){
		a[i]=(a1[i]+a2[i]*xi)%P;
		a[i+n/2]=((a1[i]-a2[i]*xi)%P+P)%P;
		xi=xi*x%P;
	}
}
ll merge(ll A[],ll l1,ll B[],ll l2,ll C[]){
    ll N=1ll<<(ll)log2(l1+l2-1)+1;
    fill(A+l1,A+N,0);
	fill(B+l2,B+N,0);
    ll inv_N=qpow(N,P-2),x=qpow(3,(P-1)/N),inv_x=qpow(x,P-2);
    NTT(A,N,x);
	NTT(B,N,x);
    for(ll i=0;i<N;i++)
		C[i]=1ll*A[i]*B[i]%P;
    NTT(C,N,inv_x);
    for(ll i=0;i<l1+l2-1;i++)C[i]=1ll*C[i]*inv_N%P;
    return l1+l2-1;
}
ll n,d[M];
ll divide(ll C[],ll l,ll r){
    if(l==r){
		C[0]=1;
		C[1]=d[l];
		return 2;
	}
    ll tmp1[M],tmp2[M],mid=l+r>>1;
    return merge(tmp1,divide(tmp1,l,mid),tmp2,divide(tmp2,mid+1,r),C);
}
ll a[M];
int main(){
    scanf("%lld",&n);
    for(ll i=1;i<=n;i++)scanf("%lld",&d[i]);
    ll S=0;
	for(ll i=1;i<=n;i++)S+=d[i];
	divide(a,1,n);
    ll ans=0,sum=1;
    for(ll i=0;i<=n;i++){
        ans=(ans+1ll*sum*a[i])%P;
        sum=1ll*sum*(i+1)%P*qpow(S-i,P-2)%P;
    }
    printf("%lld",ans);
    return 0;
}