站外题，随便看看即可

是此题弱化版

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll M=998244353;
ll n,k,ans=1,a,ny[101];
inline ll ksm(ll x_,ll p_)
{
	ll ans_=1;x_%=M;
	for(;p_;x_=x_*x_%M,p_>>=1)
		if(p_&1) ans_=ans_*x_%M;
	return ans_%M;
}
inline ll jc(ll l,ll r)
{
	ll ans_=l%M;//r%=M;
	for(++l;l<=r;++l)
		ans_=ans_*l%M;
	return ans_%M;
}
int main()
{
	ios::sync_with_stdio(false);
	//for(int i=1;i<=100;++i)
		//ny[i]=ksm(i,M-2);
	cin>>n>>k;
	for(int i=1;i<=n;++i)
	{
		cin>>a;
		ans=ans*(jc(k+1,k+a)*ksm(jc(1,a),M-2)%M)%M;
	}
	cout<<ans;
	return 0;
}

1 7075247847289146
81 

ans:492430514

输出负数