$RT$，典型的$O(N^2)$算法，然而我$AC$了

#include <bits/stdc++.h>
using namespace std;
long long k[1000005];
long long n,maxn = -0x3f3f3f3f;
int main(){
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	ios::sync_with_stdio(false);
	cin>>n;
	for(long long i = 1;i <= n;i ++)
	{
		long long a;
		cin>>a;
		k[i] = a;
		maxn = max(maxn,i * k[i]);
	}
	for(long long i = 1;i <= n;i ++)
	{
		for(long long j = n;j >= 1;j --)
		{
			if(i != j && k[j] >= k[i]) 
			{
				maxn = max(maxn,k[i] * (i + j));
				break;
			}
		}
	}
	cout<<maxn;
	return 0;
}