40分求条 谢谢

#include<bits/stdc++.h>
using namespace std;
const int maxn=20005;
int n,s[maxn];
int read(){
	int ret=0,f=1;char ch=getchar();
	while (ch<'0'||ch>'9'){if (ch=='-') f=-f;ch=getchar();}
	while (ch>='0'&&ch<='9') ret=ret*10+ch-'0',ch=getchar();
	return ret*f;
}
int main(){
	n=read();
	for (int i=1;i<=n;i++) s[i]=s[i-1]+read();
	int min_lst=0,ans=-(1<<30);
	for (int i=1;i<=n;i++){
		ans=max(ans,s[i]-min_lst);
		min_lst=min(min_lst,s[i]);
	}
	cout<<ans<<endl;
	return 0;
}