luogu2659 美丽的序列

题目

luogu2659

代码#1

以每个数为最小值，向左右扫出区间，加一点小优化

include

include

include

include

include

include

define N 2000005

using namespace std;

int n,a[N],l[N],r[N];
long long ans;

int main()
{
scanf("%d",&n);a[0]=a[n+1]=-1;
for(int i=1;i<=n;i++) scanf("%d",&a[i]);
for(int i=1;i<=n;i++)
{
int j=i;
while(a[i]<=a[j-1])
{
if(!l[j]) j--;
else j=l[j-1];
}
l[i]=j;
}
for(int i=n;i>=1;i--)
{
int j=i;
while(a[i]<=a[j+1])
{
if(!r[j]) j++;
else j=r[j+1];
}
r[i]=j;
}
for(int i=1;i<=n;i++) ans=max(ans,(long long)a[i]*(r[i]-l[i]+1));
printf("%lld",ans);
return 0;
}