POJ - 2559 Largest Rectangle in a Histogram 单调栈

单调栈的练手题，主要内容就是把每一个矩形右界限和左界限算出来比较大小就OK了。

#include <algorithm>#include <iostream>#include <sstream>#include <cstring>#include <cstdlib>#include <string>#include <vector>#include <cstdio>#include <cmath>#include <queue>#include <stack>#include <map>#include <set>using namespace std;int l[100005],r[100005],h1[100005];long long max1,p;int main(){    int n;    while (scanf("%d",&n)!=EOF&&n)    {        for (int i=1; i<=n; i++)        {            scanf("%d",&h1[i]);        }        h1[0]=-1;        for (int i=1; i<=n; i++)        {            int j=i-1;            while (h1[i]<=h1[j]) j=l[j];            l[i]=j;        }        h1[n+1]=-1;        for (int i=n; i>0; i--)        {            int j=i+1;            while (h1[i]<=h1[j]) j=r[j];            r[i]=j;        }        max1=0;        for (int i=1; i<=n; i++)        {            p=(long long)(r[i]-l[i]-1)*h1[i];            max1=p>max1?p:max1;        }        cout<<max1<<endl;    }    return 0;}