```cpp
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<cmath>
#include<map>
#include<queue>
#include<stack>
#include<queue>
#include<set>
#include<iomanip>
using namespace std;
const int MAXN=1e6+10,mod=998244353;
int h[MAXN],g[MAXN],f[MAXN];
int n,ans,maxx,minn=0x3f3f3f3f;
int main(){
cin>>n;
for(int i=1;i<=n;i++){
cin>>h[i];
// g[h[i]]++;
maxx=max(maxx,h[i]);
minn=min(minn,h[i]);
}
for(int i=-(maxx-minn);i<=(maxx-minn);i++){
for(int j=1;j<=n;j++){
g[h[j]]=0;
}
for(int j=1;j<=n;j++){
f[j]=g[h[j]-i];
f[j]%=mod;
g[h[j]]=g[h[j]]+f[j]+1;
g[h[j]]%=mod;
ans+=f[j];
ans%=mod;
}
}
cout<<(ans+n)%mod;
}
```
by 住在隔壁小莘 @ 2022-11-11 16:46:46
公差，不是方差
by 住在隔壁小莘 @ 2022-11-11 16:59:06
想出来了，是少了长度为一的情况
by 住在隔壁小莘 @ 2022-11-11 17:03:52