【UOJ】#273. 【清华集训2016】你的生命已如风中残烛

题目链接：http://uoj.ac/problem/273

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$${Ans=frac{prod _{i=1}^{m}i}{w-n+1}}$$

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<cstdlib>
#include<cmath>
#include<cstring>
using namespace std;
#define maxn 10010
#define llg int
#define md 998244353 
#define yyj(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);
llg n,m,ans,x,w;

inline int getint()
{
    int w=0;
    char c=getchar();
    while((c<'0' || c>'9') && c!='-') c=getchar();
    //if (c=='-')  q=1, c=getchar();
    while (c>='0' && c<='9') w=w*10+c-'0', c=getchar();
    return w;
}

int main()
{
    yyj("a");
    cin>>n;
    for (register llg i=1;i<=n;i++)
    {
        x=getint();
        w+=x;
    }
    ans=1;
    for (register llg i=1;i<=w;i++)  if (i+n!=w+1) ans=1LL*ans*i%md;
    cout<<ans;
    return 0;
}