HDU 1506 DP 最大完全子矩阵

记录每个位置左边大于等于它的个数，和右边大于等于它的个数

#include "stdio.h"
int le[100010],ri[100010];
__int64 ans,x,a[100010];
int main()
{
    int n,i;

    while (scanf("%d",&n)!=EOF)
    {
        if (n==0) break;
        for (i=1;i<=n;i++)
        {
            scanf("%I64d",&a[i]);
            le[i]=ri[i]=i;
        }
        a[0]=a[n+1]=-1;

        for (i=1;i<=n;i++)
        {
            while (a[i]<=a[le[i]-1])
                le[i]=le[le[i]-1];
        }

        for (i=n;i>=1;i--)
        {
            while (a[i]<=a[ri[i]+1])
                ri[i]=ri[ri[i]+1];
        }

        ans=0;
        for (i=1;i<=n;i++)
        {
            x=(ri[i]-le[i]+1)*a[i];
            if (x>ans) ans=x;
        }
        printf("%I64d\n",ans);

    }
    return 0;
}