hdu 1506 Largest Rectangle in a Histogram

#include<iostream>
using namespace std;
#define N 100002
int L[N],R[N],H[N];
int main()
{
	int i,n;
	while(scanf("%d",&n),n)
	{
		for(i=1;i<=n;i++)
		{
			scanf("%d",&H[i]);
			L[i]=R[i]=i;
		}
		H[0]=-2;H[n+1]=-2;
		for(i=2;i<=n;i++)//找左边比H[i]大的边界
		{
			while(H[L[i]-1]>=H[i])
				L[i]=L[L[i]-1];
		}
		for(i=n-1;i>=1;i--)//找右边比H[i]大的边界
			while(H[R[i]+1]>=H[i])
				R[i]=R[R[i]+1];
			/*for(int i=1;i<=n;i++) 
				while(L[i]>1&&H[L[i]-1]>=H[i]) 
					L[i]=L[L[i]-1]; 
				for(int i=n;i>=1;i--) 
					while(R[i]<n&&H[R[i]+1]>=H[i]) 
						R[i]=R[R[i]+1];  */
					
					__int64 sum=0,cont;
					for(i=1;i<=n;i++)
					{
						cont=(__int64)(R[i]-L[i]+1)*H[i];
						if(sum<cont)
							sum=cont;
					}
					printf("%I64d\n",sum);
	}
	return 0;
}