55pts问题在哪

#include <bits/stdc++.h>
using namespace std;
const long long L=5e5+10; 
long long ins,n,a[L],ans;
struct ct{
	long long pts,l;
}dp[L];
int main()
{
	cin>>n;
	for(int i=1;i<=n;++i){
		cin>>a[i];
		ins+=a[i];
		a[n+i]=a[i];
	} 
	dp[1].pts=a[1];
	dp[1].l=1;
	for(int i=2;i<=2*n;++i){
		if(dp[i-1].l>i-n and dp[i-1].pts>0){
			dp[i].l=dp[i-1].l;
			dp[i].pts=a[i]+dp[i-1].pts;
		}else {
			dp[i].pts=a[i],dp[i].l=i;
		}
		ans=max(dp[i].pts,ans);
		//cout<<i<<" "<<dp[i].pts<<" "<<dp[i].l<<" "<<ans<<endl;
	}
	cout<<max(ans,ins)<<endl;
	return 0;
}