poj2559单调栈

题意：给出连续的矩形的高....求最大面积

#include<iostream>

#include<stack>

#include<stdio.h>

using namespace std;

struct node

{

	__int64 num,pre,next;

};

int main()

{

	int n;

	while(scanf("%d",&n)>0&&n)

	{

		stack<node>Q;

		node tmp;

		__int64 ans=0,sum=0,num;

		scanf("%I64d",&tmp.num);

		tmp.pre=1;

		tmp.next=1;

		Q.push(tmp);

		for(int i=1;i<n;i++)

		{

			scanf("%I64d",&tmp.num);

			tmp.pre=tmp.next=1;

			while(!Q.empty()&&tmp.num<=Q.top().num)

			{

				node tmp1=Q.top();

				Q.pop();

				ans=tmp1.num*(tmp1.pre+tmp1.next-1);

				if(!Q.empty())

				Q.top().next+=tmp1.next;

				tmp.pre+=tmp1.pre;

				if(ans>sum)

				sum=ans;

			}

			Q.push(tmp);

		}

		while(!Q.empty())

		{

			node tmp1=Q.top();

			Q.pop();

			if(!Q.empty())

			Q.top().next+=tmp1.next;

			ans=tmp1.num*(tmp1.pre+tmp1.next-1);

			if(ans>sum)

			sum=ans;

		}

		printf("%I64d\n",sum);

	}

	return 0;

}